Never reach the bottom of the pit that is Probability 0. The game is different every time you die: the enemies you fight, the landscape you climb down, and the body you inhabit (if you so choose). Never survive. But find your way deeper than you did last time.
User reviews: Positive (43 reviews)
Release Date: Oct 1, 2012
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Recommended By Curators

"It's all about going down into the depths of madness, killing enemies along the way to up your skills & abilities, & surviving for as long as possible."
Read the full review here.


“... more focused and refined than Spelunky, or almost any roguelike.”
The Indie Game Magazine

“Probability 0 is a different kind of arcade game, one that will challenge your brain as much as your hands. Come for the endless downward action, stay for the cool upgrades you can bestow upon your character.”

About This Game

Probability 0 is a downward-scrolling infinite arcade platformer.
There are a million ways to fight for survival.

Descend: as you combat the darkness, improve yourself. Build yourself up as a star-thrower or a teleporting menace. Learn to traverse the pit's many dangers, from threatening monsters to unforgiving gravity. Walk across spikes that once frightened you. Punch through walls that would have doomed you. You'll never be invincible.

Descend: enemies grow more numerous. They will destroy the floors beneath your feet, spit death at you, and cannibalize and infect each other in their mad swarming. Your foes will be invisible, or reckless, or explosive, or seemingly untouchable. Deeper dangers will always find a way.

Descend: and die, as you did last time and as you will next time. But find your way deeper.

There are a million ways to fight for survival. There is no way to survive.


Let's talk like people, now, and not like the back of a videogame box.

I designed Probability 0 years ago, and released its first version for free in late 2009. Back then, it embraced a randomly-generated landscape (so I wouldn't get bored of it), introduced higher-order enemies to the spawn queue in a random order (so I wouldn't get bored of them), and allowed you to buy upgrades from a vast and unrestrictive talent tree (so I wouldn't get bored of those). Oh, and death wipes everything (so I wouldn't just get everything... and then get bored of playing & replaying the whole thing).

On top of that, the enemies and powers are designed to be significantly different from one another. There's an enemy who literally eats other enemies and spits their digested corpses at you. (Mechanically speaking, their 'digested corpses' are always the same handful of red globs -- but what fun is it, thinking like that?) There are more mundane enemies, of course, but one who moves in random, erratic angles is very different to fight than one who always moves straight towards you.

The set of powers, on the other hand, were made to offer you a lot of choices. There are ~36 of them and contain nearly zero arbitrary prerequisites. Buy the powers you want to have, not the boring ones you'll need for the future. Every time you level up, a new row opens up and you can buy anything from any row except for abilities that build on a lesser version of itself -- you can't get the 'never take fall damage' powerup without first having the 'take less fall damage' one. There are also none that don't augment your choices in an interesting way. You're not choosing between +10% armour and +10% damage; who cares, when you could instead be choosing between immunity to every spike in the game and upgrading your punch to kill any enemy in one hit? Those aren't even top-tier powers.

I'm still not bored of this game, and remember that it started in 2009. There are boss enemies who appear intermittently, to shake things up. There are enough abilities to try thousands of different builds, if you're feeling a little stale. There are enemies who don't even appear until you've gone deeper than I can most of the time. You'll probably die before seeing any of these things, but don't let that stop you. Keep dying.


Don't forget about JMickle's dynamic music. Its layers fluctuate as you dive deeper: the bass comes and goes; the chords swell and die; and the sirens scream as death approaches. You can hear it in the trailer, in the game itself, and even more below -- click on the soundtrack in blue and the remix album in magenta.

System Requirements

Mac OS X
    • Memory: 1 GB RAM
    • Hard Drive: 20 MB available space
    • Memory: 2 GB RAM
    • Hard Drive: 20 MB available space
    • Memory: 1 GB RAM
    • Hard Drive: 30 MB available space
    • Memory: 2 GB RAM
    • Hard Drive: 30 MB available space
Helpful customer reviews
4 of 5 people (80%) found this review helpful
0.9 hrs on record
Posted: December 16, 2014
It's not a bad game by any means, it just gets very repetitive.

The upgrades are fixed and you'll generally find yourself sticking with one set upgrade path each run because it's the only one that ever really works. The enemies move randomly and are very difficult to hit, and since the progression - at least of Beginner Mode - is done by how many enemies defeated it makes the game pretty frustrating. Also, the controls are fiddly, meaning you'll slip off platforms, walk into enemies and generally not do what you want to do. Also also, there's fall damage and a lot of the time it's unavoidable.

Altogether it plays more like a budget flash game. Try it if you've got some spare change and it's on sale.
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2 of 2 people (100%) found this review helpful
6.6 hrs on record
Posted: January 4
My go-to roguelike, great game for when I wanna play something but don't have a lot of time. Very action based, playstyles (different upgrades) vary enough, I get better as I learn from playing. There are 3 modes, one scoring based on enemies killed, one scoring on how far down you get, and one which uses points earned long-term (karma) to get a slew of upgrades from the start. This is a finished game, it seems bug-free, and runs on minimal resources. It does not have controller support, but using a keymapper program like JoyToKey would be easy enough for this game.
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45 of 56 people (80%) found this review helpful
6.9 hrs on record
Posted: June 13, 2014
The simple action of a platformer with a touch of roguelike complexity. From the mind behind Starseed Pilgrim, Probability 0 takes the straight-forward yet challenging run n' jump gameplay of platformers like VVVVVV and stirs the formula up by applying the dynamically randomized levels, skills, and enemies of the roguelite genre (Spelunky, Risk of Rain) for an end result that is infinitely replayable and impossible to master.

The challenge in P0 is refreshing, while a lot of your runs will quickly end in your swift and humiliating failure the few runs you do make it far on will feel that much more rewarding and satisfying. There are loads of powerups to play around with all located on a large and expansive skill tree that you are able to upgrade between each level you manage to surpass. Every choice will have a huge impact on how you play and every player will find their own unique path of skills on the tree to succeed by.

The game has a simple but abstract and almost horror look with a great atmosphere. There's a large variety of creepy creature designs, dark and moody colors, and a rapidly changing Probability message scrawled at the top of your screen to remind you of your impending doom. The soundtrack alines perfectly and feels dark and ominous for something so 8-bit and catchy, fitting with the mood of the game just right.

At less than ten dollars, Probability 0 is an easy buy for all fans of platforming and random roguelike elements and will be remembered by me along with the most famous of indie titles from this era.
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13 of 15 people (87%) found this review helpful
1.7 hrs on record
Posted: June 13, 2014
Probability 0 is an elegantly designed little roguelike platformer. It puts you in the shoes of an unnamed dungeon delver who has absolutely no chance of surviving the adventure, as you might have surmised from the game's title. Instead, the focus of the game is simply to delay your inevitable death for as long as possible.

There's no traditional life bar, but you can roughly tell how much health you have left by two things. One is the "probability number" near the middle of the screen, which constantly fluctuates between various encouraging statistics such as the "chance in a million that you will ever see your family again". The second way to tell how close you are to death is that the music becomes increasingly intense, and a siren can be heard in the distance. Is it the song of the valkyrie coming to take you to Valhalla, perhaps, or the grating sound of Hell's gates swinging wide in front of you? The same siren can be heard when a boss monster appears. Coincidentally, that is also the moment where you are most likely to die.

With its branching skill tree and randomized levels, the game has much replay value. Thankfully so, because each run through the game is extremely short. Progress is measured in minutes rather than hours, and a newbie might simply perish by falling off the platform they started on. You may begin to feel burned out after dying many times in a row, so I think this game is best suited for coffee breaks, or as a filler played in between other activities. What I find most enjoyable is to simply play two or three runs each session, and then stop for a while to let the lessons learned from those runs sink into my mind.

In short: If you're looking for a platformer that challenges you without wasting your time, Probability 0 is an excellent choice. It generally takes only a few minutes for your character to die, but it leaves you with the feeling of wanting to try again and to do better next time. To exact vengeance upon your killer. To see your family again... well, the probability of that happening is zero, but it's worth trying.
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10 of 11 people (91%) found this review helpful
19.0 hrs on record
Posted: October 27, 2014
This Game is the One of the Most Polished, and AWESOME Games I've ever Played.

Makes me Wonder why this Game isn't on the Featured Items Page...

I have to warn you though: This is Pretty Hardcore. Even Beginner Mode is tough.
And Expert...Yikes.

The game, like the store page says: Involves the Player to traverse increasingly difficult depths
stuffed full of Monsters who want you DEAD.
Everytime you kill a Monster: you can grab it's 'bubble' which gets you to level up.
When you level up, there are really cool upgrade trees that are instantaneously put into play.
And you start from scratch every time you die.
And you Die every time, as this game doesn't have an end.
So the Replay value of this game seems practically Infinite.

And That's Only the Beginner and Expert Modes!
There is also the Karma Mode which let's you instantly get a limited number of upgrades to start with.
But that's all you get.
Then you are thrown into a Horde of enemies.
Have Fun.
Note: Karma Mode Levels('Karma XX') build up as you play the Beginner and Expert Modes.
Note 2:When you Start the Game, it may throw you STRAIGHT into Karma Mode. And Use a Level, so don't start opening and closing the Program unless you need to.
If you aren't in to fast paced platforming where you WILL die. Then don't buy it. (But Please give it a try anyway.)
But else, BUY IT.

Don't be Discouraged that this game doesn't run on Linux though, It runs PERFECTLY on Wine(Wine Is Not an Emulator, which is a Open Source Compatability Layer that trys to get Windows Programs to Run on Linux; it isn't perfect, but it's still great.)

I think personally that Valve should team up with the Wine Development Team to Help make Wine better and get more steam games to run on Linux without requiring developers to rewrite/port their games to Linux.

My Suggestions for the Game are:
--Add a Local Multiplayer Mode: It would be Really Fun to have Either a Co-Op/Competitive Mode where 2 or more players would be trying to share the resources/trying to kill each other while simultaneously dealing with the
terrain and enemies!
--Make an infinite mode: This one is optional, but I would like to have a 'God-Mode' where I could play around and see what it would be like to have ALL THE ABILITIES AT ONCE! :)

I Definitly Recommend this Game!!!
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12 of 16 people (75%) found this review helpful
3.4 hrs on record
Posted: June 18, 2014
If you're into your roguelike-likes (you know, games like Spelunky and Binding of Isaac), Probability 0 is a must-play. You venture downwards, killing enemies to progress and collecting powers that help you beat the more difficult baddies down in the nether regions. Ironically there's a huge amount of depth to this game, and much like with Spelunky, it's only after several hours (and dozens of deaths) that you truly begin to see its full worth. You can watch my playthrough here:
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5 of 5 people (100%) found this review helpful
6.4 hrs on record
Posted: June 20, 2014
10/10 would die again.

Probability 0 is the basic concept behind roguelikes boiled down to a very few key aspects, and mixed with some clever design elements. It's pure, accessible, deep, and has an eerie, mysterious vibe to it. The platforming and combat both start out really simple, and are continuously expanded upon through new abilities (like firing your ranged projectile in new directions, being able to stomp your enemies, smash otherwise solid blocks, just to name a few). It's worth mentioning that the skill tree is extremely refined and well-designed. It feels balanced, interesting, and allows for an astounding amount of customization and experimentation at the same time.

Enemies start off really simple, but as you get deeper, the spawn pool gets mixed up with very interesting critters that drastically differ in their movement, attack pattern and other behaviour. Since each enemy and environmental hazard is extremely easy to grasp and learn, death is rather caused by multiple of these elements driving you into situations you didn't calculate. Each death, even if they are very frequent, feels more than deserved - an aspect lacking in quite a number of other games.

I would definitely recommend Probability 0 to everyone who likes a good challenge. It can be frustrating, but in the most positive way a game can be. It's pure in its design, fun to play and very rewarding.

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4 of 4 people (100%) found this review helpful
11.3 hrs on record
Posted: June 23, 2014
I picked this up on Steam a few days ago and have become slightly obsessed with it. as in, I am hearing the music in my dreams at times, and find myself humming it as I go about my day.

it's a lovely, quite melancholy trip into the abyss, in which a hapless fellow bounces about, shooting stars and trying not to run out of probability.

I'll explain that last, later.

there are three game modes --

in Beginner, the object is to scatter as many foes as possible. in short, kill them without mercy.

in Expert, it's depth that matters -- delve as deeply as possible before your chances run out.
oh, and you should probably still kill things, so you can level up... but the depth's the real thing here.

I'll get to the third mode in a moment, because a bit of explanation must come first.

when you destroy enemies in either Beginner or Expert, an experience orb appears.
sometimes it's JUST experience. sometimes it comes with 3 or 6 shots of your star.
sometimes there's a little heart inside, which does just what one would expect -- it boosts longevity a bit.

getting enough experience grants a level-up, which appears as a brightly-flashing line across the playfield. crossing the line lets the character gain a new ability (or improve an existing one),
as well as cancelling any fall and healing the same as though one had picked up a heart.)

in this game, the health meter is insane.

there's a rapidly-changing set of phrases and numbers in top-center, all expressing probability of some desired outcome.
when a run begins, these numbers are in the 5-6 digit range mostly, but as your fellow takes damage, the numbers dwindle -- when you see 1-3 digits and hear the warning siren coming into the music, it's time to be super careful.

that same siren also sounds, much more loudly, whenever a particularly dangerous enemy boss shows up.

eventually, luck runs out, and one's left staring at a big fat 0 under some statement of what could have been... but won't be, no matter how much you play.

death is inevitable here, but it can be really fun getting there.

finally, I'll mention the third mode -- Karma -- which is what makes P0 even more awesome.

playing Beginner and Expert runs gives Karma credit.

Karma maxes out as 10 ("X", in game terms). when playing a Karma run, you get to select as many abilities as the number of Karma levels allows, and go through an even-harder-than-expert run to prove your mettle. (you also lose 1 level of Karma each time you do a Karma run, but it's not terribly hard to regain the level by playing Beginner/Expert a few times.)

in this mode, collecting the orbs enemies leave after death is the object -- which makes it the most difficult thing, especially since Karma mode teems with enemies who can easily get in the way of scoring the spoils of recent kills.

in short, it's very replayable and lots of fun. my only real regret is that it doesn't have more variety of music, but that's not such a big deal, as the music that it DOES have totally fits the action.
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4 of 4 people (100%) found this review helpful
0.8 hrs on record
Posted: September 9, 2014
There is no point to this game but the challenge. No achievements, no online, multiplayer, co-op, or leaderboards. No saves. Nothing to unlock. No steam cards. None of that.
What yu DO get is two difficulties, Beginner and Expert. Beginner is hard enough. You get your own personal high score. Not scoreboard, just score. Then you get one other mode called Karma, where you get to test your skills with preloaded abilities, but no leveling up at all. If you ever played Fall Down on the TI83/83+/84+ calculator, it's a bit like a twisted version of that.
Don't get me wrong, this is not an awful game, but it is a matter of preference. There is no incentive to playing this game other than your own satisfaction in the challenge and testing your skills.
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4 of 5 people (80%) found this review helpful
7.5 hrs on record
Posted: October 6, 2014
Severely underrated, bombastic music and endless replayability. KNEES SHOULD BE A PASSIVE NOT AN UPGRADE THOUGH SERIOUSLY GUYS THE FALL DAMAGE HURTS SO BAD.
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2 of 2 people (100%) found this review helpful
3.5 hrs on record
Posted: June 28, 2014
If I were to describe this game in one sentence: A mad effort to survive!

Risk injury to kill monsters to level up, or avoid dangerous groups of them but miss a chance for experience. Beware! For the more monsters you avoid, the less powerful you will be deeper down. And to have a hope to survive what lies there, you will need every skill you can get.

This game makes me feel like I am playing a pixelated Mario in a downscrolling platformer on a Gameboy. That's great, in case you didn't know!

3 game modes, beginner, expert, and karma (where you use your previous deaths in other game modes to level yourself up before the game begins, allowing you access to high level skills and builds right from the beginning. however, the monsters are furious and numerous. how long can you survive?)

1 wicked soundtrack that changes as you near death!

1 diabolic UI that numbers your days! (the numbers generated become smaller as you become more injured)
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6 of 10 people (60%) found this review helpful
1.6 hrs on record
Posted: June 13, 2014
Like a streamlined Spelunky, great "fun-to-die" game. Highly recommended.

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1 of 1 people (100%) found this review helpful
1.9 hrs on record
Posted: June 30, 2014
Probability 0 is a pixel rogue-like platformer with no end. You're some unnamed protagonist, stuck in a downwardly-descending level with no way out and no way to survive. You have no way of determining your health aside from the intensity of the music, and, if it's really low, the color of your eyes. If you die, you go back to the start, but hey, there's a skilltree that resets and the level, if you missed the "rogue-like" part, is always randomly generated, so it doesn't get boring.

That's more or less it, really.

A great game if you're a fan of platformers and rogue-likes or just want something you can pick up and put back down in maybe 10-30 minutes. Maybe if you're at an airport and waiting for someone with your laptop, or on a car trip and your laptop can't handle anything super complex, this would be perfect.

Wish it was maybe a dollar less, but I wouldn't consider it overpriced for the amount of content.

Overall, 8/10.
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2 of 3 people (67%) found this review helpful
5.8 hrs on record
Posted: August 6, 2014
If you're a fan of 2D action platformers and the roguelike genre, you will probably enjoy this game. The game is unforgiving even in the 'Beginner' difficulty. You don't have a health bar in the traditional sense, instead the game prominently displays the 'probabilities' of several events occuring. Events such as: 'Choices resulting in a second chance', 'Chance in one million that you escape unharmed' or 'Ways to achieve anything but death'. As you take damage the numbers displayed for each of the events slowly approach zero. When the probabilities reach zero, you die.

In the standard game modes, you either break blocks or kill enemies to gather stars, when you gather enough stars you get an upgrade and there is a subsequent increase in difficulty. The game also increases in difficulty as you slowly descend. And descend you must, as the screen slowly scrolls down. If you go too far off the screen vertically you will automatically die. You will also automatically die if you fall off the screen and touch an area of the bottom border where there are no blocks to stand on.

There is a free demo available to play, which I would recommend doing if you're considering a purchase. The demo is what made me ultimately purchase Probability Zero.
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9 of 17 people (53%) found this review helpful
0.2 hrs on record
Posted: June 24, 2014
My favorite part of Metroid, except forever with karate.
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4 of 8 people (50%) found this review helpful
1.1 hrs on record
Posted: June 13, 2014
Getting this was probably one of the better ideas in my life. This game is amazing and Droqen is great. Glad it's on Steam now so I can remember to play it too much.
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4 of 9 people (44%) found this review helpful
0.8 hrs on record
Posted: August 19, 2014
Okay, hm, think of it like... Spelunky. It's a simpler, more intense Spelunky. That's honestly the best I can put it. It's pretty fun...

...except that it's too repetitive. It just doesn't have the complexity needed to encourage me to keep playing. It's got random levels, but not random enough that it doesn't feel like a different experience every time.

Maybe if it was cheaper, like a 50% off sale. But not at full price.
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0 of 1 people (0%) found this review helpful
2.8 hrs on record
Posted: April 30
Beautiful little rogue-like platformer.

It begins with a simplistic concept that as you get to the lower levels, unlock upgrades that change the nature of the game completely. The first few upgrade tiers seem trivial, then quickly turn more complex and powerful reaching the higher ones. You can craft quite a few builds, whether you're going for versitile or just plain tanky.

Buy it.
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4 of 10 people (40%) found this review helpful
0.4 hrs on record
Posted: September 9, 2014
Its based on a free flash game on web.

-No fullscreen support, you have to play it in a little square on screen.
-No achievements.
-Not even trading cards.

Why they put this one on steam, and put a price tag on it? Totally cash grab.
If youre wondering, just search google and play its demo for free. Its almost same game, you'll get the idea.
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0 of 2 people (0%) found this review helpful
0.4 hrs on record
Posted: June 19, 2014
Hey guys, Just wanted to show this game. Extremely fun rogue like platformer game. I really think some fo you would enjoy it. Check it Out!!
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