In the original Half-Life, as Gordon Freeman makes his way to work on that fateful day in the Black Mesa Research Facility, you find a break room. A scientist sits at a table drinking from a coffee cup, and another paces the room. Then you see it. A microwave with a container of some unidentifiable food within, begging to be interacted with. There s no button prompt on the screen telling you to do so, but you just know that if you press the use key next to it something will happen. Something incredible. Something messy.

So you press it, and it beeps. Nothing. You press it again, and this time it beeps at a slightly higher pitch. A clue that you should keep pulling this thread, even though it looks like nothing is going to happen. So you hammer the use key until, suddenly, the dish explodes. The microwave is covered in yellow gunk and the pacing scientist rushes over. My God! he exclaims. What are you doing? He sadly observes the mess you ve made, but Freeman says nothing. You walk away, no apology, no remorse. Classic Gordon.

Valve knows what we re like. If we see something, we re going to try and interact with it. Doubly so if it looks like it was never meant to be interacted with, or if it s out of reach. And it s great that games like Half-Life reward this very human curiosity. There are few things in videogames more satisfying than hitting the use key next to some prop, and something happening in response. When it doesn t, it s always a disappointment. It makes the game world feel somehow more lifeless, more artificial. Like you re in some kind of cardboard film set rather than a real place. If I ever move near a hand dryer in a videogame bathroom and it doesn t roar into life, my immersion shatters into a thousand twinkling pieces.

I feel for the developers, though. They have to dedicate time and resources to modelling, texturing, animating, and creating sound effects for the most mundane objects. But it s work that s always appreciated. In the latest Deus Ex game, Mankind Divided, Adam Jensen s apartment is a funhouse of stuff to switch on and mess with, from the flushing toilet to the washer and dryer that start rumbling when you power them on. Eidos Montreal didn t have to do any of this stuff, but it makes all the difference that they did.

Flushing toilets, incidentally, have become the go-to test of a game s interactivity. There are even websites cataloguing all the games that feature them. Because it s the internet, and of course there are. Be honest: the first time you encounter a toilet in a game, you try to flush it. You probably even do it without thinking, instinctively hitting the use button when you re near one. And if nothing happens, and you don t hear that familiar rush of water, you wonder if the game s even worth your precious time.

In the years since Half-Life was released, the exploding microwave is still perhaps the best example of this kind of interaction. But there are others. Human Head s 2006 shooter Prey opens in a brilliantly interactive bar, boasting a TV with channels you can switch, playable gambling and arcade machines, and a jukebox with tracks by Judas Priest, Blue Oyster Cult and other classic rock groups. It s completely unnecessary, and doesn t reflect the rest of the game, but it speaks volumes that people still mention it now. In fact, I can t really remember anything about Prey except the bar scene.

Some games even make a feature out of switching things on. In Hitman, turning a radio on or getting a sink to overflow is a frequently invaluable way to lure a guard away from his post. But often you need a certain item to turn said thing on, such as a wrench or a screwdriver. IO Interactive has cleverly looked at how people love interacting with objects in games and designed a system around it.

Environment artists are doing incredible work these days, giving you increasingly detailed, atmospheric worlds to exist in. But no matter how complex the geometry is, how high-res the textures are, and how gorgeous the skybox is, it won t matter if we approach that toilet, press the use key, and it doesn t flush. As games get more expensive to develop and assets get more time consuming to make, I hope developers never forget that, above all, people just love turning things on. The toilet must always flush.

I find myself increasingly interested in gaming history as I get older, from Digital Antiquarian to Matt Chat. This post from Half-Life writer Marc Laidlaw was right up my alley, then, as it whisked me back to November 9 1998, or the day after the original Half-Life was released. As Laidlaw states in the preface, the text is taken from a recently discovered word file that he seems to have written on that date: a document that discusses the evolution of Half-Life, from the time he was brought onto the project to the time it eventually shipped, over a year later and after a significant delay.

Whether it was written on that date or not, it's a fascinating summary of the game's development, one that offers insight about creativity in general, and the way projects morph over time from their creators' original visions. Give the whole thing a read, is what I'm saying, but here are a couple of choice quotes to grab your interest:

"We tried out and discarded quite a few grand schemes. Some of you may remember, as I do, early talk about how there would be no bottlenecks in the game; how you would be able to run from one end to the other and all the way back again. This would have been a very easy feature to implement, given the nature of our transitions, but I was very relieved when we jettisoned this notion. Total freedom for the player would have meant a total loss of dramatic suspense. All narrative forms of drama, but especially horror, rely on pacing and rhythm. In horror timing is crucial. You have to set up your traps just so, and wait until your victim is precisely in position. There s nothing worse than springing them a moment too soon or too late. This would have been virtually impossible to control in a nonlinear game. would have been choosing to throw all suspense right out the window. We really wanted players to have an artfully structured experience, and time and trial have basically proven that the most satisfying narratives are linear."

"The one noticeable casualty of the camera s elimination was the absence of Gordon Freeman himself, our main character, as a visible presence in the game. Apart from the loading screen and the multiplay menus, and on the box itself, you never get to see Gordon Freeman. This introduced an interesting challenge. How could we make a real character out of someone you never saw, and who never uttered so much as one word? Well, we let the player solve that problem for himself. You start the game knowing very little about Gordon; but apparently everyone else knows you who you, and they fill you in on their expectations. In the gray zone between the player s ignorance and the NPCs knowledge of Gordon, something rather interesting happens. Players create their own Gordon Freeman a character they can identify with completely. There is nothing to jar you out of Gordon, once you re in the game. He never says anything stupid that you would never say in a million years. He never does anything you wouldn t do since you are behind all his actions. He becomes a hollow receptacle into which every player pours himself."

Digital trading cards are simultaneously one of Steam's smartest and most sinister features. Each game that supports them (and most do these days) has a set of cards, ranging in number from just four or five to more than a dozen, that are earned simply by playing the game. Collect a full set and you can exchange them for badges, wallpapers, and other such goodies, and also boost your Steam user level.

The catch is that you can only earn half of the number of cards in a given set that way, and some of them might be duplicates. So if you want them all and you do then you'll have to either trade with other users, or buy them with real money from Steam's Community Market.

Interestingly, and unexpectedly, one of the games on Steam that doesn't support this particular dopamine pump is Valve's own Half-Life. It was meant to: As ValveTime reports, Valve actually hired artist David Thany to create Half-Life cards, badges and emoticons for the 2013 Steam Summer Sale. But they were never used, possibly, according to Thany, because they appeared more akin to the sequel, Half-Life 2, than the much more primitive-looking original.

I don't know if he's right about that, but it's a fair point. If I'd seen these images without any introduction, there's no question I would have assumed they originated with Half-Life 2. Even so, it's a bit odd that three years down the road, nothing else has been added in their place. It seems clear enough that Valve wanted Half-Life trading cards, so what's the holdup?

I have no idea, but these are pretty great. And Thany's work did make it into at least one game on Steam: The Hotline Miami trading cards are his creations, too.

Joe Wintergreen is an Australian indie game developer who is currently working on mostly a stealth FPS under the Impromptu Games banner. He also recently delivered unto the internet a series of code snippets from the great FPS Half-Life 2 by way of his Twitter account. There's not much to see of the code, but that's not why we're here. What's really relevant are the code comments, and the light they shine on how the magic is made.

The first tweet in Wintergreen's thread sets the tone for what's to come:

Good to know Valve and I pretty much have the same comments in our AI pic.twitter.com/TrWO8KUAadSeptember 1, 2016

Striders will intentionally shoot things up even if you're not in their line of sight, just because it looks cool:

Strider might still shoot if it knows it won't hit ya if there's something there it'd be cool to hit pic.twitter.com/fHwWO7Cw6CSeptember 1, 2016

Charlie don't surf, and the Combine don't dance:

A fix to make combine soldiers not dance. pic.twitter.com/aXDrhAUk5gSeptember 1, 2016

Zombies had to be toughened up after the shotgun's power was increased, to keep things in balance:

Cool little comment about rebalancing zombies after some changes to the shotgun happened. pic.twitter.com/XxM3ntFm4vSeptember 1, 2016

This is a stupid fix but it works, so whatever:

Might as well continue this thread since I found another good HL2 comment. Feel validated, everyone! pic.twitter.com/gYBCZJJvaRSeptember 2, 2016

There's only one fuck in the entire codebase, according to Wintergreen, and this is it:

Respect to Valve for having only one "fuck" in the entire HL2 codebase. pic.twitter.com/zKNF4ygjIvSeptember 2, 2016

Alyx Vance: Nice girl, handy in a fight, terrible eyesight:

Ah, good bit of HL2 Ep1 commenting (kind of thing they'd put in the dev commentary). On Alyx/barnacles in the dark pic.twitter.com/DhYyooJOyGSeptember 2, 2016

Some of comments really give a sense of what goes into making a game and keeping it intact. One in particular is actually a multi-paragraph telling of how the Strider minigun was accidentally nerfed in the Orange Box because of a bug in the original Half-Life 2 that nobody noticed. There's also a bit about the low violence mode, and references to the Combine Advisors, large sluglike aliens with creepy psychic powers who ended up not being used in the game. [Correction, sort of: I've been reminded that they did appear in Half-Life 2: Episode 2, but you didn't actually fight them.]

It's a fun bit of videogame history, and there are quite a few more than just what's embedded here. If you've got a few minutes, you can catch the entire thread on Twitter.

Fellow PC gamers, we are gathered here today to remember an old friend, one whose warranty expired long ago. As laid out in the law of the upgrade cycle, we must let go of those components that can no longer keep pace with modern demands. And so, it is with heavy hearts that we say our final goodbyes to you, our constant companion for the last 20 years.

Rest in peace, humble optical drive.

You were once a cornerstone of this community, a bringer of joy, a portal to play, an ally in our pursuit of entertainment. You gave us the gorgeous world of Myst, the sublime soundscape of Quake, the unprecedented complexity of Half-Life. You were a marvel of your age, drawing realms of infinite possibility out of those small, innocuous discs. At the time, it felt like nothing less than magic.

Nearly 30 years ago now, you entered this world with a vision. Armed with Red Book audio and full-motion video, you sold us the Hollywood dream, treating us to Mark Hamill taking on a race of giant cat aliens, Jeff Goldblum killing it as Dracula, Christopher Walken telling it to us straight, and... this immaculate performance. Video games seemed poised to replace movies altogether; why would we watch if we could play instead? Alas, it was not meant to be, but we'll always have those fond memories, thanks to you. Your legacy will live on inside us all.

As we commit you to the great server in the sky, let us reflect on all the good you did for this world. Who can forget how crucial you were during the dial-up days? The spiral cords of our 56K modems strained under the weight of individual mp3s; the thought of downloading an entire 750MB CD-ROM was unfathomable. Even when cable internet arrived on the scene, we still relied on you to support us through the file-size boom of the DVD era. Steam might have dethroned you eventually, but your stability during the platform's early, rocky years was what kept us gaming.

In your youth, your laissez-faire attitude allowed our community to flourish unabated. I, personally, owe some of my favourite childhood memories to your liberal approach to game trading; as a kid, hiring and borrowing games was the only way I could afford to play. Thanks to borrowing a friend's copy of Diablo II, I discovered my penchant for click-'em-ups. Thanks to renting Battlefield 1942, I grokked the appeal of online multiplayer. Thanks to hiring out Baldur's Gate II, I realised that games could tell big, complex stories that actually leveraged their interactivity instead of ignoring it. Of course, we all understand why you had to jump on the DRM train once people started abusing your freedoms. Still, those unbridled early years were crucial in making our community as great as it is today.

Alas, those halcyon days are far behind us. The battle of the distribution models is over, and there's no question who lost. How could it have gone any other way? Steam lets us pre-order, pre-load, patch, and play, all without leaving the comfort of our desk chairs. Gone are the overloaded shelves buckling beneath the weight of bejewelled CD cases and boxy collectors editions. Never again do we have to rummage around in dusty attics and dank basements to find that old copy of Day of the Tentacle, only for you to whine like a circular saw when we put the disc in because it isn't mint-out-of-box.

For all the joy you gave us, we cannot ignore the dark times you begat. Refusing to read brand new discs until we'd carefully wiped off every minute mote of dust. Scratching up our favourite games as punishment for playing them too much. Demanding that we 'Insert Disc 2' when it was already in the damn tray. And those multi-disc installs! How can you expect us to set aside multiple hours just to swap GTA 5's seven DVDs in and out?

At least you re in a better place now, one where the RPMs are infinite and the CDs are truly scratch-proof. Because as much as it pains us to say it on this day of mourning, you were holding this industry back. Bite-sized games never stood a chance against the pains of disc-swapping. Aspiring developers cringed at the cost of pressing and shipping discs. If we hadn't moved on to the all-digital now, we'd never have known the haunting oppression of Papers, Please, the touching tale of Gone Home, the time-bending antics of Superhot. We'd have to bid farewell to our hundreds-large Steam libraries or else buy a second house just to store all the CDs.

The fact is, old friend, we simply don't have the space for you anymore. Not in our homes, and not in our hearts. Your place at the top of our PC towers is no more. Our mini-ITX cases no longer give you a berth. We will never again hear your mechanical whirr, your voice silenced by the hum of our bigger and better hard drives. From caches to ashes, from disc to dusk, your time is up. You re just too slow for this digital world.

16X. 8X. 4X. 2X. 1X. Eject.

Every game is ambitious. It s not easy to turn a beautiful idea into a finished, playable game as developers have said time and again, sometimes it feels almost impossible. As miraculous as finishing any game might be, not all games are created equal. Some stretch the boundaries of technology to their breaking point. Others take a leap into the unknown with new design schools, often so effectively that years later, it s hard to remember them ever having to be invented.

Think, for example, of Monkey Island s Three Trials structure, as used by almost every adventure afterwards. Or its sequel s Four Map Pieces , as later picked up by BioWare. And sometimes, both art and science combine to push the envelope and we get something truly, impossibly special. Here are our picks for the top 20 ignoring the very early games that had to prove computers could handle gaming at all.

For more on some of the most monumental games ever to grace the PC, check out our feature on the most important PC games.

King's Quest (1983)

For the longest time, adventure games were where people looked to see the latest innovations. King s Quest set that bar early on, jumping from simple text and pictures to 3D environments, huge worlds, and a fairytale land of mystery to both wander and wonder at. Admittedly, the last part was helped by some dreadful puzzles. King s Quest was originally commissioned by IBM as the showpiece for its long-forgotten PCJr system, but the series would go on to demonstrate just about every major technological advancement for the mainstream: ADLIB sound, VGA graphics, full speech, and high resolution. 3D didn t work out so well, but until that point, King s Quest was where many players went to get their glimpse of the ever-advancing future.

Commander Keen (1990)

If you want to experience pure hell, try the average 80s PC platform game. Long before making Doom, the team that would be id Software wanted to prove that the PC could handle experiences that played as smoothly as dedicated consoles. Commander Keen wasn t just a fluid experience by the standards of the time, but a fast one, with pogo-jumping, shooting and big levels to explore. Looking back, it s hard to appreciate what a development it was, but we re talking an era where games like the original Duke Nukem (or Nukum either way, the one who wore a pink suit and watched Oprah) were constantly being held up as the PC s answer to Mario. Commander Keen didn t qualify either, but it paved the way for many sequels and the formation of id itself.

A bit of bonus ambition: before making Keen, id tried to convince Nintendo to let it port Super Mario Bros. 3 to the PC by building a working demo (in their off hours in a single week, no less). Nintendo said no thanks, but you can see footage of the demo here.

Maniac Mansion (1987)

If you made a game like Maniac Mansion right now, people would still rightly call it ambitious. A choice of seven characters, each with their own skills. A non-linear adventure with five different endings depending on choices and characters. Real time elements, like ringing the doorbell and having a character come downstairs to check on it. Puzzles involving multiple characters in different rooms of the house or simply the option to do things like put a kid in an empty swimming pool and then fill it back up. And on top of all of this, Maniac Mansion brought the world the SCUMM system (Script Creation Utility For Maniac Mansion) that would define about half the adventure game market for the next decade. All of this, in 1987. Few adventures have ever done so much.

Ultima Underworld (1993)

Like most of the games on this list, Ultima Underworld is a fusion between ambitious technology and ambitious design the design side specifically being to take one single dungeon and try to breathe life into it. To add nuance to its different races, there to be talked to instead of just beaten up. The Stygian Abyss wasn t just a battlefield. It was a fallen community. A place to live in. The experience of being thrown into a dungeon and just expected to survive.

What really sold it though, if your PC could run it, was the technology. Before even Wolfenstein 3D, Ultima Underworld offered a full 3D environment complete with slopes, lighting effects and more, in a bit of technology that could only have been more impressive if well, the viewing window had been a bit bigger. Underworld 2 greatly increased the scope of the game, visiting other worlds and making it a bit easier to see, but what the first one managed remains a technological victory worthy of any heroic age.

Ultima VII: The Black Gate (1993)

Get used to seeing the word Ultima. Ultima VII came out in 1993, and still games like Divinity: Original Sin measure themselves against its success. Its biggest success was creating a living world, where peasants went home at night, weather blasted the world, your companions had to be fed, and, yes, where you could get some flour and water, mix it into dough, stick it in an oven, and get your own deliciously crispy bread. On top of this was an incredibly mature story that continued the series love of more advanced storytelling than most games of the era (previous ones having tackled racism, the perversion of good, and the quest for a hero worth being called one) with a complex tale of good intentions subverted by an otherworldly being of pure, but incredibly smug malevolence.

Ultima Online (1997)

Last time! Where Ultima VII brought a living world to single-player RPGs, Ultima Online brought it to multiplayer. It wasn t the first MUD or MMO, but most of them followed the Diku model popularised by Everquest: go forth, slay. Ultima Online wanted to create an actual world, where players would gather resources, craft houses, become shopkeepers and more, with hero just one of the many careers available. It wasn t without its problems, the first of them being the discovery that given a world to explore and exploit, players will typically turn it into a survival of the fittest Hell. But, its scope, its potential, and the joy of it when it worked created an epic experience that s still running today, and stories like the assassination of Lord British that will never cease to amuse.

The Elder Scrolls II: Daggerfall (1996)

The second of the Elder Scrolls games asked one hell of a question: could you make a world with over 750,000 characters and a map the size of Britain actually feel like a world? We re putting this one here instead of Elite, partly to ring the changes, but mostly because few procedural games have pulled it off so well enough political relationships, guilds, interesting stuff to discover, and cool mechanics like being able to get turned into a werewolf or vampire.

It s not that difficult to create raw space. Daggerfall s own predecessor Arena offered even more. Its sequel, Morrowind, did what most games tend to, and hand-crafted a far smaller area in intricate detail. But for a moment with Daggerfall, we had a game that showed you could be epic, procedural and interesting, without simplifying everything down to the ASCII style of Rogue or putting all the impetus on the player to pretend that there was more going on behind the surface than was ever going to meet the eye.

Duke Nukem 3D (1996)

While another case of a game that s not aged all that well, Duke Nukem 3D was the game that took FPS action out of military bases and sewers and relocated it to city streets, cinemas, and other more realistic locations. That plus a complicated scripting system to blow them all up, clever tricks to fake a 3D engine (even though it was only 2.5, much like Doom) and endless imagination took Duke from being a moderate shareware star to the highest tiers of game characters. No wonder the world was willing to wait so long for Duke Nukem Forever. Even if it wasn t worth it, in the end.

Outcast (1999)

The PC has never really had its own Legend of Zelda. Action. Exploration. A whole new world to explore. Outcast is arguably the closest its come.

A graphical powerhouse of a game that immediately impressed with its freedom, with the AI of its characters, with the glorious effects in everything from jumping into water, to your personal scanner rippling gridmarks across the scenery. There was only one problem. It was all done with voxels at a time when 3D cards were finally allowing for decent polygonal worlds, putting all the work on CPUs that couldn t handle it. If you could play it, Outcast was an unforgettable experience. Too bad for most people it was one that had to wait until the GOG version that finally made it run, long after its prime.

Grand Theft Auto 3 (2001)

It s easy to dismiss the sheer effort that goes into creating a city. After all, we ve walked, run, driven and carjacked around so many. GTA 3 wasn t even the first, with racing games in particular having set the pace. But could you get out of the racing cars and ramble? Enjoy a pumping gangster soundtrack? Run around with automatic weapons and go on missions with a huge cast of crazy characters? Just sit back and listen to an hour of talk radio? Nope. GTA III was magic, and so many sequels on, it s still raising the bar for what virtual cities can and should be.

Give or take a few terrible cock jokes, anyway.

EVE Online (2003)

Ultima Online intended to let players call the shots. It didn t quite work. With EVE Online however, CCP had the courage to actually let it happen, creating one of the most talked about online games of the last few years. Tales of empires at war, of con artistry on a scale that would make Count Lustig blink, the epic sagas of backstabbings and betrayals that no other game can match. CCP likes to describe EVE using the phrase EVE is Real , and while there may not be any starships flying distant galaxies under your favourite forum s command, they still have a point.

Civilization (1991)

All of human history in a single game? There s not much more to be said, really. As achievements go, the only bigger one would be making it one of the greatest games of all time. Not to cast aspersions on the likes of Elite for creating a universe in slightly fewer bytes than the average person would make in a toothpaste and peperami footlong, but the thing about space is that it is mostly empty. Just saying. The world however, in as many ways as you can imagine? That s ambition, even if using it educationally does mostly teach people never, ever to mess with Gandhi.

Deus Ex (2000)

Real world. Real conspiracies. Where do we even begin? Deus Ex not only set out to create some of the most realistic real-world locations we d ever seen (not a tautology the games before hadn t exactly done a great job most of the time), but also turn them into nothing short of a psychopath s toolbox. Multiple paths and solutions. Characters who reacted to your decisions. Tiny decisions determining who lives and who dies. All wrapped in some of the best writing and wrapping the PC had known up to this point. There s a reason why so many years on, it s the original Deus Ex that still stands out as both one of the greatest games ever, and the template of a dream for future immersive simulators to study at the feet of as they try to surpass it.

Dwarf Fortress (2006)

Simulations don t get any deeper than this. Literally, or figuratively. Dwarf Fortress or to give it its full title, SLAVES TO ARMOK: GOOD OF BLOOD, CHAPTER II: DWARF FORTRESS is an ASCII gem best summed up by its creator saying in 2011 that we shouldn t expect version 1.0 for at least twenty years. That s what you get in a game so crazily detailed that a cat can go into a tavern, pick up spilled alcohol on its paws, wash itself off, and get drunk. This was never intended behaviour, just the sum of smaller sub-routines coming together and making their own reality. In retrospect, that twenty years to complete doesn t sound so much at all.

Half-Life 2 (2004)

In a way, Half-Life 2 s most ambitious part isn t even in the game. Valve had an idea for a new store, called Steam . You might have heard of it. Half-Life 2 was, if not its Trojan horse, then its vanguard. You wanted to play the best FPS ever made at the time? Then you got it through Steam. And that worked out pretty well.

Even if you ignore Steam, Half-Life 2 reinvented the shooter with its focus on physics, with every chapter introducing new mechanics and new exciting concepts like the gravity gun or playing point-defense with turrets. It also created a continuous world like no other, putting the final nail into the coffin of games that didn t prize a sense of presence as well as place in their shooter campaigns. Much copied, but still rarely bettered, Half-Life 2 set out to be both the best shooter around, and its next great leap forwards.

Planetside (2003)

Some games just shouldn t be possible. Even knowing the technology that powers them, the epic battles of the Planetside series have always had a degree of magic to them. For the handful of players lucky enough to have a system and connection that could handle it, heading out into one of Planetside s huge battles is a defining moment in games. For the rest, it says a lot that it still felt just as impressive when Planetside 2 rolled along only a couple of years ago. 5v5? 12v12? That s all well and good. But an explosive, expanding, all-access battlefield where the war never stops? That s military action with a little sorcery mixed into the formula, even today.

Spore (2008)

It failed. Yes, we know. It failed. But this is ambitious games we re talking about, and few games shot higher than Spore. Leading a tiny organism through every stage of life. Constructing it using the surprisingly powerful and fun editor. Sending it out to meet other players aliens in a great throbbing galaxy full of freshly created life. That may have been the point where the charm ran out, but the open-ended action and procedural generation and early focus on user generated content that led up to that point still stands out as a technological, if not gaming success.

Crysis (2007)

"But can it run Crysis?" was a relevant joke among PC gamers for at least three years for good reason: well after 2007, Crytek's shooter could still bring CPUs and graphics cards to their knees. Crysis took Half-Life 2's early use of physics and applied it to a dense, free-roaming world. Being able to shoot a tree, watch it fall over, and then shoot the trunk into smaller pieces was revelatory players gladly gave up framerate in favor of insane graphics and physics processing. Cutting edge AI and the systems-driven sandbox gave Crysis the depth to match its insane graphics, and no shooter since has managed quite the same combination of wow and substance.

DayZ (2012)

From its beginnings as a popular mod, DayZ spawned one of the most popular genres in gaming today. The framework for this multiplayer zombie survival game was Arma 2, up until that point one of the most ambitious simulation games and a bastion for fidelity and scale on PC. DayZ built upon Arma 2 s ambition, borrowing and later adapting its 225 km2 terrain, Chernarus, which was created from satellite-modeled slices of the Czech Republic.

The month that DayZ caught on, creator Dean Hall was already laying out incredible plans about features he wanted to add, as he told us in an interview. Underground structures. Dog companions. Realistic disease systems. A couple months later we were hearing about destructible terrain and player cities. Part of Hall s stated approach was to experiment with big, bad ideas, but the reality of implementing them quickly in Arma s Real Virtuality engine for DayZ proved to be a massive challenge.

Outside of these early technical roadblocks, as a multiplayer game DayZ was uniquely trusting. The systems that DayZ inherited from Arma granted it some depth, and being dropped into a massive, hostile environment with no instruction empowered players to tell their own stories, often through surprising, weird interactions with other survivors.

Our 2012 mod of the year remains in Early Access after arriving on Steam as a standalone game on December 2013.

The Witcher 3: Wild Hunt (2015)

It s amazing to think that in just three games, CD Projekt Red has gone from unknown studio to absolute top-tier RPG developer. The Witcher 3 is their masterpiece, from the hand-crafted world to the sheer number of characters and plots. It s a game that excels on every level, from scripting subtle enough for a character to break off combat when they hear your name, to the global nature of some of the most amazing graphics and scenery in any PC game ever, and the sheer artistry of just about every major quest or aside. You never know what s coming next, from the teary humanity of the Bloody Baron s agonising storyline, to a gaggle of Witchers drinking too much, dressing up in drag, and drunk-dialling wizards across the whole continent.

Star Citizen (20XX?)

No, it s not out yet. It doesn t matter. Chris Roberts play to create the ultimate space game already qualifies. Elite style action combined with a dedicated, AAA Wing Commander-style campaign starring Mark Hamill. First person action aboard ships. Deep space exploration. A persistent universe allowing for company, or the solitude of the stars. A crowd-funded budget of $117,259,371 and counting, with players happily putting down real money for in-game ships and unlocking features like pets and modular ship designs and new AI characters to scatter around on planetside environments. If it s not the greatest game ever, expect literal, physical riots.

WASD feels inevitable today. Once mouselook became standard in 3D games, it made little sense (at least for right-handed players) to hold your left arm across your chest to reach the arrow keys. The WASD keys were more comfortable, and offered easy access to Shift and Space. But even though WASD seems like the obvious choice now, far fewer players used it 20 years ago.

Our favorite four letter word was never a foregone conclusion, and didn't become standard through some gaseous enlightening that spread to every PC gamer simultaneously. The new movement scheme took several years to catch on, and while we can t know whose fingers found their way to WASD first, we do have a good idea of who popularized the style: the greatest Quake player in the universe, Dennis Thresh Fong.

Fong made history when he took home John Carmack's Ferrari 328 after winning the first-ever nationwide Quake tournament in 1997. And when he won that tournament, defeating Tom "Entropy" Kimzey on Castle of the Damned, his right hand was on a mouse, and his left hand was perched over the four keys we now consider synonymous with PC gaming. But even then, not everyone played that way.

In the early days of first-person shooters, Fong says the keymappings were all over the place, and even the great Thresh had only just started to play with a mouse at all. Imagine him just a few years before, sometime around 1993, as a teenager losing a match of Doom against his brother Lyle. Like many Doom players, Fong used only the keyboard. Without the need to look up or down, it was a natural choice so much that using a mouse was even considered weird. His brother, however, was playing with a keyboard and trackball, and he was winning. It wasn t every game both were excellent players but Lyle won enough that one summer Fong decided he had to learn to play with a mouse. After that, he was unbeatable.

Right after I made that switch, my skill improved exponentially, says Fong. Pretty much, from then on, I never lost.

It took some experimentation including a strange attempt to move with WADX but Fong settled on WASD and has been using it since Doom. Did he invent the scheme? No, probably not. Others were also gravitating to the left side of the keyboard for Doom at the same time. But without Fong's influence, the default could have ended up different. It might have been EDSF, or stranger configurations like ZXC to strafe and move backwards, and the right mouse button to move forwards. Some early shooters bound movement to the arrow keys. In 1994, System Shock used ASDX, while Descent used AZ for forward/reverse and QE for banking (if you didn't happen to have a joystick).

Fong tells us he even knew a player who used ZXCV to move.

I m certainly not going to take credit for the creation of [WASD], says Fong. I stumbled across it. I m sure other people started using it as well just based on what was comfortable for them. I definitely think I helped popularize it with a certain set of gamers, particularly the ones that played first person shooters."

It s likely that he did. The very concept of a professional gamer was new at the time, and Fong was well-known on the west coast as the best player around. As Fong s celebrity grew, the one question everyone asked him was: What s your config? His answer could be most readily found in Thresh s Quake Bible, which describes the WASD formation as an inverted T. And his guide carried weight. Even before his success as a Quake player, Fong was a Doom champion, and so people imitated him, just as the kids at the basketball court by my house spend far too much time trying to hit Steph Curry s 30-foot shots.

The evidence can be found on old bulletin board systems. In one thread from 1997, a poster recommends using Q and E to strafe and A and D to turn. Another suggests using the keypad for movement, and someone else says they use A, Shift, Z, X. It wasn't the case that everyone simply gravitated to the 'obvious' choice of WASD or ESDF, and in another thread, we see how Thresh's performance in the Quake tournament spread his style. His play was so impressive, the poster looking for his config speculates that it was impossible for him to turn so fast with a mouse.

Another legend, Quake programmer John Carmack, took note. Even when I was hanging out with Carmack, wherever, at E3, random people would come up and he would hear them asking me what my configuration was, says Fong. So he ended up building a Thresh stock config into Quake 2.

It was a relief. Not only could Fong sit down at any computer with Quake 2 and instantly load his configuration, every time he got the question, all he had to say was type exec thresh.cfg.

Convenient as it was, Fong doesn t think the inclusion of his config was the main factor in the rise of WASD, and I d agree. By the time Quake 2 was out, WASD was starting to feel like common knowledge. I used it, and I don t remember hearing Thresh s name associated with it at the time, though it s possible his configuration entered my consciousness two or three people removed.

And yet games, strangely, took a while to catch up. Carmack may have bundled Thresh s config with Quake 2, but when it released in 1997 the default controls were still arrow keys. A year later, though, that changed. If Thresh's Quake tournament win was WASD's first watershed moment, the second came in 1998 with the release of Half-Life. The Quake and Doom players at Valve perhaps influenced directly or indirectly by Carmack, Thresh, and other top Doom and Quake players included WASD in Half-Life s default keyboard and mouse config, which helped solidify it as the first-person shooter standard.

Valve engineer Yahn Bernier checked Half-Life's original config file for us and confirmed it included WASD. "I remember finalizing this file (maybe with Steve Bond) during the lead up to shipping HL1 but don t recall specifics about when WASD was settled on or really why. We probably carried it forward from Quake1 " he wrote in an email.

The same year, and less than a month after Half-Life, Starsiege Tribes also made WASD default. Quake 3 followed suit in 1999, and WASD's popularity grew even more. It was also the default binding in 2000's Daikatana, but Half-Life, Tribes, and Quake 3 probably had a bit more to do with its popularity.

There were still plenty of heretical control schemes in 1999 like System Shock 2's, which defaulted to WADX (and S for crouch). But WASD had momentum. If it wasn t already ubiquitous by 2004, World of Warcraft defaulting to WASD codified it for millions of PC gamers. Now it s in RPGs and MOBAs and even strategy games, controlling camera movement over maps.

Interestingly, Valve boss Gabe Newell doesn t use WASD. I personally don't like WASD as it takes your hand away from your typing home keys, he wrote in an email to PC Gamer. I always rebind to ESDF. Newell's not alone there. Do a little Googling and you'll find plenty of people arguing that ESDF is the more natural configuration.

More surprisingly, another Half-Life developer, level designer Dario Casali, also rejects WASD. Instead, he prefers ASXC. It feels natural to me, where WASD feels odd, wrote Casali. But lots of people scoff at my config.

What would PC gaming be like had EDSF or ASXC been Half-Life s default? No offense intended to Newell or Casali, but I shudder to think of it. ASXC just sounds bonkers to me. Newell's fairly commonplace ESDF is more palatable, but as Thresh echoes, it feels harder to hit Shift and Control while easier to mispress one of the surrounding keys. For me, Thresh, and millions of PC gamers, it s WASD for life.

You can read more about the history of Quake in our retrospective celebrating Quake's 20th anniversary. We're also celebrating by running a Quake server through the weekend, and Thresh himself will be playing on our US-West server today, Friday, from 3:30 pm - 4:30 pm Pacific time.

Wes Fenlon also contributed to this article.

Modding Half-Life 2 is still an enriching pastime for thousands, but did you know you can mod life to be more like Half-Life 2? Yeah, it's a thing: Russian handyman Valplushka has fitted a remote control drone with all the adornments needed to make an authentic Half-Life City Scanner drone.

It's a pretty impressive setup: the front panel moves emotively, just like in the game, and there's a red laser light embedded inside. The mind boggles at the potential. I'd like to have one as a pet, actually.

The first video is a simple demonstration of the drone, while the following one gives you some idea of how to make your own. Cheers, Geek.com.

I can't remember how long it took me to finish Half-Life 2. It's been a while, after all. But I can say, with absolute confidence, that it was a lot longer than the breathtaking 40:49 it took the SourceRuns Team to do it.

As is usual with speedruns, this is not a typical playthrough of Half-Life 2. It's done using a 2006 build of the game that used the original engine, which has significant movement differences, as well as a long list tricks and glitches that have since been patched out. It's also segmented, which basically means that it's a group effort: Different players hammer through different bits of the game, and the best of them are stitched together into what you see in the video.

The net result is fast, furious, and funky, as the runners clip through walls, fly over levels, and blow past the talkie bits. It doesn't look like much fun in the conventional videogame sense, but it's a hell of a sightseeing tour, and a remarkable accomplishment, coming in at just one-third of the world-record mark the SourceRuns team set in 2013.

A spreadsheet that breaks down just about every element of the run you can imagine is up on Google Docs, and the SourceRunners have also posted a separate video explaining how clipping works on YouTube.

Half-Life 2 turns 12 this year, and thanks to its powerful, if a bit creaky Source engine it remains as popular with the modding community as ever. Over the years we've seen all manner of excellent mods emerge, adding co-op or competitive multiplayer, shiny graphical updates, new story content, and even full conversions that bear little or no resemblance to the original game.

It's the latter two we're going to focus on today, as we round up the best single-player Half-Life 2 mods. We've chosen mods that stand up as separate adventures, sometimes set in worlds far removed from Combine Earth.

The Stanley Parable

This is the story of a man named Stanley. Or rather, it's the story of the story: a deviously clever, reactive adventure that second-guesses your every move. As Stanley or, perhaps more accurately, as the player controlling Stanley you're free to follow or ignore the various instructions the wonderful narrator bellows over you, resulting in a tangled, branching story that rewards your curiosity, imagination, and defiance. The original Source mod was later expanded into a full game, one our Phil thought extremely highly of in our review.

Download: ModDB, Steam.

Minerva: Metastasis

Adam Foster's Minerva comes close to the quality of Valve's own Half-Life 2 Episodes in fact, Valve was so impressed Foster joined the company. It's a sizeable story, about the length of an official chapter, with considered level design and a high level of polish. You begin the game strapped to the underside of a helicopter, before being dropped on a mysterious island with a sinister secret.

Download: Steam.

The Citizen

Gordon Freeman ends the Half-Life series as a crowbar-wielding superhero, a figure of legend in the Half-Life universe. Two-part mod The Citizen provides a new angle on the world, casting you as an ordinary oppressed citizen of City 17. Obviously, said ordinary man soon acquires a gun and starts killing people, but you might snap too if you called that dystopia home.

Download: ModDB.

Get a Life

This lengthy, ambitious mod swings from horror to all-out action. Occasional cutscenes tell the story of a subway technician suffering from leukaemia, but Get a Life's unlucky hero Alex also has to contend with the mod's new limb damage system, which causes effects like dizziness and limping, depending on where he's hit by enemies.

Download: ModDB.

Mission Improbable

Your mission, should you choose to accept it, is to step into the sneakers of Gordon Freeman and set off to repair a Resistance listening post. This impressive Episode Two mod begins with Gordon rowing to a distant coastline: a coastline that reminds you just how pretty the venerable Source engine can look in the right hands. The right hands in this instance are a couple of established game devs, and their experience shines through pretty much every crevice of this slick, well-paced adventure.

Download: ModDB.

Research and Development

Thanks to its then-revolutionary ragdoll physics, a lot of time in Half-Life 2 was spent throwing chairs at NPCs, or flinging teacups with the gravity gun. In that spirit, Research and Development does away with offensive weapons altogether, leaving just a couple of secondary tools to let you manipulate gravity or order Antlions about. Puzzles are the order of the day here, and it's surprising just how easily Half-Life 2's toolset translates to this new focus.

Download: ModDB.

Nightmare House 2

Where there are modding tools, horror mods are sure to follow. You don't need to have played the original in fact, it's included as a prologue, giving you the chance to explore both a haunted house and a spooky hospital. The horror on offer here is mainly of the jump scare variety, so if you were hoping for the psychological horror of Silent Hill, move on to the next item in the list. Nightmare House 2 is basically FEAR it even features its own creepy ghost girl but more FEAR is hardly a bad thing.

Download: ModDB.

Silent Hill: Alchemilla

The impressive Alchemilla drops you in the world of Silent Hill, endless fog, Dark World and all. Not only have the developers nailed the grimy aesthetic of Team Silent's classic series, they've matched its colour palette, borrowed its sound effects, and recreated its lonely atmosphere. It's such an uncanny representation that it may take you a while to notice there are no enemies traipsing around, but then those games were hardly known for their satisfying combat.

Download: Alchemilla mod.

Water

Until now everything we've featured has been strictly first-person, but Water bucks that trend. In fact, it bucks a lot of trends, given that it's a third-person puzzley adventure starring a mermaid. Yes, a mermaid. While you're (initially at least) limited to a fantasy city's waterways, this smart mod soon finds ways to get you exploring land too, using a number of innovative systems. The developers of Water went on to make From Earth, another, similarly inventive Source mod.

Download: ModDB.

Black Mesa

Well, we couldn't ignore Black Mesa, could we? For the unaware, this recreates the original Half-Life in its sequel's shinier engine, and it's been in development since dinosaurs roamed the Earth. Much more than a simple port, Black Mesa updates Valve's game with fancier assets, new voice acting, a reworked campaign and more. The team have also excised Half-Life's much-maligned Xen section, albeit only temporarily until it's been remade to be, somehow, good. While the older mod is free, you'll find the newer version on Early Access, accompanied by a price tag.

Download: Official site.