As many movies and videogames have taught us, robots will one day take over the world. Steam's Fellow Humans sale which is running from right now until tomorrow at 10am PT/6pm BST asks that you accept this fact, in exchange for some sweet deals on robot-related games.

Such as the science fiction horror spectacle Soma, which is on sale with a 60 percent discount at 9.19/$11.99. The wonderful physics-meets-philosophy puzzler The Talos Principle is just 7.49/$9.99 with 75 percent off, and each entry of the Five Nights at Freddy's series is half price which means the first is 1.99/$2.49, while the rest come in at 2.79/$3.99.

A sentient Steam statement reads:

"I, like you, enjoy breathing air, bipedal motion, having skin, and playing video games. Being a human requires a great deal of input and may result in circuit fatigue. For this, I recommend video games. Playing video games may heighten cardiac undulation, dilate optical sensors, and result in diaphoresis. These symptoms suggest a human like myself is feeling...

"Happiness. Video games result in happiness. Thus, fellow humans, prepare to download the Fellow Humans Sale. This is not a malfunction. Do not attempt to adjust your process servo. You too can feel happiness by saving the city, enacting your free will, and totally not being a robot."

Other gems include Grow Home at 2.99/$3.99, its sequel Grow Up at 5.35/$6.69 and Machinarium at 2.79/$3.99.

The Fellow Humans sale is on now until Friday, October 7 at 10am PT/6pm BST.

Peter "Durante" Thoman is the creator of PC downsampling tool GeDoSaTo and the modder behind Dark Souls' DSfix. He has previously analyzed PC ports like Dark Souls 3, written an open letter to PC developers, and more.

Dive into a forum discussion about a new PC game, and one word will inevitably show up: optimization. Deus Ex: Mankind Divided? "I think this game is not optimized AT ALL!" writes one player on Steam. Metro: Last Light? "In a few words optimization in this game is terrible," writes another.

Complaints about bad optimization are often shorthand for 'this game doesn t run well on my PC.' But is that performance really the fault of the game s programming not being written as efficiently as possible? How do you really know if a game is poorly optimized, or simply pushing your PC to its limits?

This article will try to clarify what optimization actually is, give an overview of some technical features like lighting and anti-aliasing that are inherently computationally expensive, and shed some light on how developers actually determine graphics presets and system requirements. Thanks to Croteam and QLOC for providing invaluable insight into the process of optimization.

To make it more digestible, this article has been split up into the three pages. Page two features the densest technical discussion, so jump to page three if you mostly want to know about how optimization is carried out.

Page 1: A brief definition of optimizationPage 2: A guide to the graphics settings that heavily impact performancePage 3: How games are optimized, examples of optimization, and how optimization is misjudged.

What is optimization, and can we measure it?

Optimization in gaming discussions doesn t mean the same thing it means in computer science. Rather than referring to making a process optimal, it generally means making things better. The crucial difference is that in computer science, optimization is only considered as such if it produces the exact same outcome.

As a very simple example, if you wanted to calculate:

a = b*c + b*c + b*c

Instead, calculating:

d = b*c, and setting a = d + d + d

would be an optimization it only requires one multiplication rather than three for the same result. By this strict definition, the idea of comparing the level of optimization across distinct games trying to accomplish different things becomes completely impractical.

So how do we talk about game optimization while maintaining some level of objectivity? Here s the definition QLOC gave me:

"Good optimization means that the game works at the same framerate across a wide range of hardware specs, including low-end configurations."

Maintaining that reliable framerate is where they see the importance of graphical settings, since they can bridge the large technological gap between low- and high-end PCs.

Croteam s Dean Sekulic, who has been optimizing games for more than 20 years, believes that "on the one hand, no, you cannot compare whether different games are optimized or not", but that it should be possible to form a judgement by looking at the quality of the output produced by two different games and the relative performance they achieve. However, he cautions that "there are also lots of things under the surface" that influence how a game may perform.

What kinds of things? Understanding optimization, and what affects it, means answering that question. We ll start with judging the performance impact of graphical effects that are especially demanding on current hardware.

On the next page: the graphics settings that most dramatically affect game performance.

High-end effects and their performance impact

If you aren t getting the performance you expect out of a game, there s a good chance one of these settings is to blame. These are the biggest obstacles to smooth performance, and should be the first you adjust to hit that 60 fps target.

Image quality

Perhaps the single most performance-intensive setting is also very easy to factor into optimization comparisons: rendering resolution. Since it generally boils down to just two numbers (like 1920x1080) and is available across almost all games, comparing at the same resolution comes naturally. An important fact that sometimes gets overlooked is that rendering effort scales with the number of shaded pixels 4k is roughly four times as expensive as 2k, not two times.

Anti-aliasing is a far more complicated topic when it comes to comparability. In a modern game you might find any of the following:

• Pure screen-space methods, like FXAA or SMAA (1x). They look at the final rendered image and try to find and mitigate aliasing artifacts like stair-stepping using post-processing.
• Temporal accumulation anti-aliasing methods. They render the image at slight offsets each frame and accumulate the results while trying to compensate for movement.
• Multisampling (MSAA) at various levels involves taking multiple samples per pixel at polygon edges.
• Supersampling (SSAA) at various levels uses multiple samples for all pixels.
• Combinations of the above (e.g., TXAA).

These are listed above in ascending order for their expected performance impact, except for the combination category which depends on the cost of its components. Screen-space methods are generally cheap, pure temporal accumulation is only slightly more expensive, followed by multisampling and finally supersampling. Multisampling presents particular difficulty in performance comparisons, since its cost in performance can vary significantly based on the implementation, from very cost-effective all the way to close to supersampling. Supersampling is relatively easy to relate to resolution: Nx supersampling is similar in cost to rendering at an N times higher resolution.

Lighting and shadowing

Surfaces and atmospherics realistically responding to light form the basis of 3D graphics, and at the same time its holy grail. More complex effects are continuously being developed, and given the fidelity available today, further visible improvements often come with a significant performance cost.

In terms of lighting, almost anything that bills itself as volumetric or an approximation of global illumination is often justifiably expensive. This includes high-end implementations of so-called god-rays, which try to replicate the effect of bright light illuminating airborne particles or dust in front of a darker backdrop.

Where there is light, there should be shadows, but sadly this does not occur as naturally in games as it does in the real world. In modern games, there are usually at least two sources of realtime shadows: ambient occlusion, which tries to account for overall reductions in illumination usually based on close-range surroundings, and direct shadowing.

Ambient occlusion, when it was introduced in Crysis, was a significantly expensive effect all by itself. These days, high-quality screen-space ambient occlusion is no longer a huge performance drain. However, new techniques such as voxel ambient occlusion or occlusion based on distance fields, which set out to fix issues inherent in screen space methods, once again come with a significant performance impact at this point in time.

With direct shadows, contact hardening is a difficult effect to replicate in games. This describes the fact that shadow outlines appear sharper and more defined close to the shadow caster, and progressively softer the further the point where the shadow is cast moves away from it. There are a number of different implementations of this behaviour around (e.g., PCSS), but it s never a cheap effect to replicate.

One important thing to remember when discussing optimization: everything that responds to unpredictable realtime changes lights moving or changing intensity, players moving, or in the worst case even the terrain being altered is far more performance intensive than light behaviour and shadows that can be precomputed. If a game has dynamic daylight cycles or terrain deformation, that needs to be heavily considered when discussing the performance of its lighting and shadowing solutions.

Miscellaneous effects

Many other effects that do not fit into either category above relate to simulating the optical behavior of a camera system. These are often not too performance-intensive, with the exception of high quality bokeh depth of field effects. The blurrier an out-of-focus part of the image should be, the higher the potential performance cost.

A relatively recent development often encountered together with Physically-based rendering (PBR) are screen-space reflections. These are less expensive than traditional reflections, which would require rendering large parts of the scene again, but can still have a significant performance impact. This is doubly true if they simulate advanced characteristics such as contact hardening.

Finally, there is a category of effects related to physical simulation, which can cause a significant computational burden on either the CPU, the GPU, or both. For non-gameplay purposes this is most common in the case of hair and cloth simulation, followed by the simulation of fluids, gases, debris, and their dynamic interactions.

On the last page: Common misconceptions about optimization, and how developers optimize games and determine graphics presets.

Aspects of optimization

Now that we have some idea about some of the most expensive effects in modern games, we can dig into what it takes to create a game that will, hopefully, end up being considered optimized.

Determining presets and system requirements

Graphics presets the common low , medium , high , very high , ultra are almost never directly comparable across games, but they are very important: they guide gamers who do not want to dive deep and adjust individual settings.

At Croteam, a basic 'medium' target is set early in a game s development, based on hardware constraints and expectations, and all design and artwork adheres to that standard. Closer to release, the technical team then derives settings for each preset, trying to balance graphical splendor and performance at each level.

What I personally love about their approach is that they categorize each performance option as either CPU-bound, GPU-bound, or memory capacity-bound, rather than leaving it to the user to figure that out. While they try to design presets to accommodate a balanced PC, this approach makes it easier for gamers with a particularly strong or weak GPU or CPU to make effective use of their hardware.

For QLOC, who mostly deal with porting existing console games to PC, the standard console settings usually translate to the 'medium' preset of the PC version, though some aspects might be tweaked to accommodate essential platform differences. Scalability options are then provided to whatever extent is feasible. Both presets and requirements are continuously evaluated throughout the optimization process, starting as soon as the renderer and other core features are tested and working.

How presets and hardware requirements relate is often a bit of an unknown to gamers. While every developer has their own standards, for Croteam 'minimum' specifications mean that the game will run well at low settings, and if those requirements aren t met full technical support will not be provided. 'Recommended', on the other hand, means that the game can be played as intended ("Not medium: high", as Dean told me) at 1080p resolution.

How we judge optimized games

Armed with more knowledge of what goes into optimization and some of the most expensive effects, we can now try to reconsider some hotly debated examples of 'unoptimized' games.

One relatively recent subject of this debate was Dying Light, and in my opinion it is one of the most damning cases not due to the developer, but due to the misguided reception it received. Dying Light is an open world game with lots of moving actors and parts as well as a dynamic day/night cycle, all ingredients that make up a technically demanding game. It shipped with a huge range of settings for draw distance in particular, which in this type of experience greatly affects both CPU and GPU load.

There was an outcry about the 'terrible unoptimized PC port' when Dying Light would not perform up to (arbitrary) standards at maximum settings. As it turned out, the draw distance slider in the initial version of the game was already above console settings at its lowest position, and went incomparably higher. People were so agitated, in fact, that the developer felt like they had to reduce the range of the slider to 55% of its former maximum in an early patch.

Would the game have been perceived as much more 'optimized' if this trivial step would have been taken before release? I definitely think so. Would it actually have been better optimized ? No, absolutely not. Dying Light is a great example of just how difficult it can be to judge optimization, and also of the concerns developers might be limited by when implementing game options.

A similar issue occurred very recently with Deus Ex: Mankind Divided, which prominently featured an MSAA setting (up to 8x). As the game uses deferred shading a common rendering technique that makes a straightforward hardware-accelerated implementation of MSAA much less viable this setting came with the extreme performance impact one would expect in such a renderer. Again, the game might have been seen as far more 'optimized' had it not included that option, and again this is obviously not the case.

Game are rarely a single monolithic entity that is either optimized or unoptimized. There might be individual effects that are not very well optimized while the majority of the engine is. This is particularly common with novel features: When the original Crysis first included ambient occlusion, the effect was not particularly optimized compared to modern implementations. Similarly, the first implementations of voxel-based AO in Rise of the Tomb Raider a well-optimized and beautiful game overall might well be outperformed significantly in the future.

Metro 2033 was one of the first games to broadly implement volumetric lighting, and was considered as a spiritual successor to Crysis in its performance impact at higher settings. And the same goes for recent and future implementations of contact-hardening shadows. However, I consider this experimentation with new features essential, even if their initial implementations might not be broadly usable due to their performance impact. This is how games progress toward more advanced, more optimized effects in the future. The beauty of the PC platform is that what was an 'unoptimized' effect in 2010 can be rendered at great framerates and make a game look better even on midrange hardware in 2016.

Of course, games that are well and truly unoptimized as a whole do exist. There s usually a backstory: limited resources, a small developer biting off more than they can chew, or a lack of technical skill. Still, when a game stutters even at its default preset on powerful hardware, or a relatively simple 2D game drops down below 20 FPS on a modern console, then even the most well-meaning analysis leaves no room for other conclusions. Most cases, however, are more difficult to judge, and I hope that this section illustrated that point clearly.

Optimization challenges

The actual process of true code optimization (in the practical computer science meaning outlined earlier) is challenging. For Dean Sekulic, the 'worst optimization nightmare' is "looking at a profiler output and seeing the top function take 3% of the time." To give you a high-level idea of what this means, profilers are tools that tell a programmer how much time is spent in one particular function of code, usually sorting those functions by time spent.

When the top function takes 3% of the time, this means that even if you manage to improve it to be twice as fast which might require herculean efforts the complete program will only speed up by 1.5%. Since these situations are common in large, competently written code bases, optimizing them further becomes a gradual, laborious task.

QLOC, which ports games based on a wide variety of technologies, see their challenges vary a lot with each project. "Things can be really hard in one game, and far less troublesome in another." One common, difficult aspect they identify is making sure that the game performs well across a very wide range of hardware.

Overall, "there are no silver bullets" in program optimization, as Dean put it.

Optimization is not just about graphics!

Given the general focus of online discussions and reviews, as well as this article so far, this is a point that should be reiterated: optimization is a topic that concerns more than just graphics, although they obviously make up a very significant chunk of the processing time a game spends each frame.

As the development team at QLOC put it: "For us, optimization is also a lot about improving poor decisions with the controls, the gameflow and UI, tweaking the save/load system, improving netcode, and even fixing old bugs from the original title." I can imagine that this point of view is one appreciated by many who had to fight with mouse acceleration, input lag or byzantine UI decisions in other ports and I ve reported on a fair share of those myself.

Wrapping up

Despite all this detail, this article only very lightly scratches the surface of what goes into optimizing a modern PC game. I hope it provided some insight into the development process, as well as perhaps some hints on which settings to disable if you ever find yourself in need of a few extra FPS.

It wouldn t have been possible in its current form without insight from the good people at QLOC and Croteam. Croteam offered the perspective of a long-term PC-first developer known for the technical quality of their games. QLOC is known primarily for their porting efforts, and their involvement usually makes PC gamers anticipating a game breathe a sigh of relief. Any errors you might find are mine, not theirs.

I d like to close this article with two appeals:

When you compare the relative performance of games, try to take into account what they are actually accomplishing. As discussed above, realtime lighting and interactive objects are incomparably harder to present at the same fidelity as static scenes, and there are some graphical phenomena reality throws at us even minor ones that are performance intensive to replicate regardless of how optimized their implementation is.

In a similar vein, consider the idea that additional high-end graphics settings, even if they are not fully usable at the time of a release, are never a bad thing compared to not having those settings available in the first place. Their presence doesn't make a game unoptimized. I ve always believed that coming back to a high-end game many years later and seeing it in even more splendor is one of the many major perks of the PC platform, and it would be sad to see this diminished due to shortsighted judgments about optimization.

The Talos Principle was a game that really clicked with me. I'm not even very good at puzzle games normally, and I rarely have the patience to get far with them, but this one pulled me in on an emotional level; its philosophical musings may have dime-store shadings, but I was happy to buy into them, especially wrapped as they were in Elohim's soothing voice, the bright, beautiful game world, and all the ridiculous secrets it had hidden away which actually had a reason for being there.

All of which brings us to the point that The Talos Principle 2, or whatever it ends up being called, is (maybe, hopefully) in the works. Rock, Paper, Shotgun noticed a tweet from a Nordic Games Conference attendee named Damir urovi , who said that Croteam's Alen Ladavac revealed during his presentation that Talos Principle 2 is going to happen. That's pretty thin, yes, but Croteam gave the report a little more weight by retweeting urovi 's message.

Yes, "Talos Principle 2 is going to happen" confirmed by @AlenL @Croteam on stage @NordicGame 2016! pic.twitter.com/lAMXaMJk4sMay 20, 2016

Of course, there's also the fact that The Talos Principle was a surprise hit and probably brings more mainstream appeal to the table than Croteam's main franchise, Serious Sam the latest version of which, by the way, is being written by Talos Principle co-writer Jonas Kyratzes and his wife Verena. (Why Serious Sam needs a scriptwriter in the first place, I could not say.) A sequel seems rather obvious, in other words. But Croteam and publisher Devolver Digital are remaining coy about it for now; in response to my inquiry, a rep confirmed that Alen said something about it at the Nordic Games Conference, and then laughed at me.

The Talos Principle is known for its story. Serious Sam is not. That these two so utterly different videogames come from the same small development studio has always tickled me, but it never occurred to me that, aside from a few goofball easter eggs, the two could actually cross over in any meaningful way. I mean, how could they?

And yet somehow, it's happening. Not within the games themselves, but in their creation, and in a way I can only describe as bizarre: Jonas Kyratzes, one of the two writers of The Talos Principle, and his wife Verena have signed up as the "screenwriters" for Serious Sam 4.

"I was a fan of Serious Sam before I got to work with Croteam, so I must admit I was sort of hoping I might be involved with the next one if The Talos Principle went well. But more than that, we immediately clicked with the team, were treated like family, and really wanted to keep working with them," Kyratzes said. "Going to Croatia and working in the office just confirmed that."

Croteam offered no insight into what direction the plot to Serious Sam 4 will take (and that may be the most mind-boggling thing I've written all week), but said the Kyratzes are "shaping the story into something really awesome." I can't even begin to guess how that will work out, but it's worth remembering that The Talos Principle actually began life as Serious Sam 4, before evolving level mechanics led the studio to turn it into a whole new game. Since it's likely that some of those Talos gameplay elements will make it into the next Serious Sam, maybe it's not so weird that the writing would, too? 

Yeah, no. It's weird.

A new expansion has been released for brain-bending philosophy-'em-up The Talos Principle. It's called Road to Gehenna, and it follows Elohim's messenger Uriel as he journeys through four new worlds. It is likely to be just the ticket for anyone looking to dismantle more fans, place more jamming devices and redirect more lasers.

Can you solve the puzzle of how to watch this trailer? I have faith that you can.

The Talos Principle was really good, so I'm glad to see there's more of it now available. It sounds like a sizeable amount of new content, too. That's reflected in the 11/$15 price tag, although you can currently get Road to Gehenna for 10% off until July 30.

Is it any good, though? We should have a review up tomorrow—just as soon as Chris's head has stopped hurting.

I really liked Croteam's narratively complex puzzle game The Talos Principle, and fortunately for my self-esteem, so did Chris when he played it for our review. I was thus very excited about the March announcement of an expansion called Road to Gehenna, and today we finally got wind of the release date: July 23.

The Talos Principle: Road to Gehenna will unfold over four chapters with "some of the most advanced and challenging puzzles yet." Players will take on the role of Uriel, Elohim's messenger, as he tries to free the souls trapped in the game's strange, mysterious world. The expansion will feature new characters and a new world with its own unique history and philosophy, created by Tom Jubert and Jonas Kyratzes, the writers of the original game.

The Road to Gehenna expansion will be out on July 23. More information will be available on Steam when this link goes live—in the meantime, enjoy some screens.

Mario Kotlar, level and puzzle designer for The Talos Principle at Croteam, has as many instruments around his desk as he does screens. Though, I think "desk" is a generous description for a pair of small tables, but to each their own when it comes to setting up your space. Personal comfort is the priority. With a keyboard (the piano kind), a Cintiq, and a laptop to compliment his rig, Kotlar has a lot of options crammed into not very much room. He was kind enough to show off his desk and PC, as well as tell us why he—perhaps predictably, being a puzzle designer—loves the Portal games. 

What's in your rig?

• Operating System: MS Windows 7 Ultimate 64-bit SP1
• CPU: Intel Core i7 2600K @ 3.40GHz, Sandy Bridge 32nm Technology
• RAM: 16.0 GB Dual-Channel DDR3 @ 668MHz (9-9-9-24)
• Motherboard: ASUSTeK Computer INC. P8Z68-V (LGA1155)
• Graphics: NVIDIA GeForce GTX 770
• Monitors: SyncMaster (1920x1200@59Hz) and a Cintiq 13HD (1920x1080@60Hz)
• Hard Drives: 977GB Western Digital WDC WD10EARS-00MVWB0 (SATA), 2TB Western Digital MyBook, 3TB Western Digital MyBook, and a 232GB Storejet 25 Transcend
• CPU cooler: Contac 29 BP
• PSU: Coolmaster 700W
• Keyboard: AKAI MPK49
• Mouse: Zowie Mico
• Speakers: Logitech Z523
• Laptop (ancient): DELL Vostro 1700
• Guitar: Floyd Rose - X-Cort
• Table: no comment :)

What's the most interesting/unique part of your setup?

It has to be either the shittines of the table, or having 3 instruments around together with the Wacom Cintiq. Or could it be apple keyboard hooked to a windows PC? My setup is weird...

What's always within arm's reach on your desk?

Other than the obvious, plain old boring bottle of water and some candies, not featured in the photos I'm afraid.

What are you playing right now?

I've got FFXIII and Life is Strange on hold, and I occasionally still sometimes play SC2, GW2 and Portal 2.

What's your favorite game and why?

Portal 1 and 2, I'll never forget the mindfuck of conceptualizing non euclidean space for the first time. And then there's both perfect gameplay and perfect story setting tied into it.

Tom Jubert, one-half of the writing team behind the outstanding first-person puzzle game The Talos Principle, has provided a little bit of insight into what's coming in the Road to Gehenna expansion. He wasn't interested in repeating what had already been done, he wrote in a recent blog post, so he and writing partner Jonas Kyratzes kicked around some ideas that would "expand on the original world without simply following in its footsteps."

Among the ideas pitched and discarded were setting the expansion in the distant past, when the Elohim system was still in development, or in the distant future, after it's been discovered by other beings; or putting it on a separate server with the same rules but different archive information, resulting in completely different versions of Elohim and Milton, the game's nagging voice of doubt and cynicism.

Jubert didn't offer any hints about what they and Croteam eventually settled on, but said it "provides us huge flexibility in terms of the sort and tone of material we deliver. It gives us a world that fits within the original game's religious and science fiction mythology, but which resolutely has its own identity. Most importantly for me, it lets us explore completely new ideas about how to interact with the game." He also described it as "ambitious," adding that the script is comparable in size to that of The Talos Principle itself.

"We have consciously designed [Road to Gehenna] to be experimental," he wrote. "We wanted to explore new ideas in a safe environment so that when we inevitably come to Talos 2 we will be able to raise our audience's expectations once again."

Jubert said the expansion is now undergoing "final bug-hunting," and will be out in the next month or so.

I have been assured that this is not in fact an April Fool's joke, and thus I deliver the news that you may now opt to replace the smooth and soothing voice of Elohim, the godlike overseer of The Talos Principle, with the rather rougher tones of Serious Sam.

It will still be Elohim's words and wisdom guiding you through the existential maze that makes up your journey through The Talos Principle, but the new DLC pack means they will delivered by Serious Sam voice actor John J. Dick. The DLC also includes a new Serious Sam player model, for those who'd prefer the game to be a little less serious. (Which is ironic, I know.)

Injecting one of the ultimate embodiments of the thick-headed FPS macho man hero into a game that's essentially a slow-paced meditation on the meaning of life, consciousness, and personhood might seem counterintuitive, but that dichotomy has been one of my favorite things about The Talos Principle from the very beginning. That the studio that gave the world "No Cover. All Man" would conceive of a game like this in the first place is flat-out weird. That it would do such a good job of it almost beggars belief.

The Serious Sam Voice Pack DLC is free until April 7, after which it will be available for purchase for $3. The Talos Principle itself, along with all other DLC, is on sale on Steam for half-price (that's $20) over the same duration.

Brain-taxing puzzler The Talos Principle is getting an expansion, publisher Devolver has announced. Called the Road to Gehenna, it will cast you as Elohim's messenger, and will send you through a new, previously hidden chunk of the simulation. Fun fact: Gehenna has all manner of religious significance, and could also theoretically contain lasers you can redirect.

A four-episode add-on, Croteam is promising the most advanced and challenging puzzles yet made for the game. It'll also feature new story from the main game's writers, Tom Jubert and Jonas Kyratzes.

"We wanted to revisit the world of The Talos Principle and deliver new characters and a new world with its own history and culture, said Jubert in a press release. With Road to Gehenna we have created an all-new narrative which both branches off from and expands the original character s journey."

The Talos Principle: Road to Gehenna is due out this Spring.