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:
Mostly Positive (50 reviews) - 76% of the 50 user reviews for this game are positive.
Release Date: Oct 1, 2012

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“... 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
    • Storage: 20 MB available space
    • Memory: 2 GB RAM
    • Storage: 20 MB available space
    • Memory: 1 GB RAM
    • Storage: 30 MB available space
    • Memory: 2 GB RAM
    • Storage: 30 MB available space
Helpful customer reviews
5 of 6 people (83%) found this review helpful
0.5 hrs on record
Posted: February 27
I was unaware that Downwell had any competition in the "low-res roguelike platform descent" genre until my friend put me onto Probability 0. There's less of a setup and more of a high-concept motif here, with your silhouetted pixel man descending into a never-ending pit of darkness, battling strange monsters along the way. You start out only punching and slinging stars downward, but defeating enemies levels you up and allows you to select from dozens of new abilities across several tiers. There's space for some actual builds here, such as ones heavy on punching, or stars, or defense, or contact damage, and so on.

Despite the advancement options, there's not much variety of gameplay to use them on. You'll encounter more and stranger monsters the further down you go but the basic structure of the pit doesn't change from assortments of blocks and spikes. It's not necessarily a bad thing, it just strays closer to an infinite runner than, well, Downwell. The fixed scrolling also means your pace is mostly dictated by the game, making Probability 0 feel the more measured and technical of the two.

The title refers to the game's most unique aspect, the probabilities that constantly flash across the upper center of the screen. This is essentially your health, as the random probabilities decrease as you get hit, from six digits all the way down to singles. It's a clever touch that really supports the surreal, striking feel of the game you get from the stark graphics and steady, low-fi soundtrack. There's two difficulties to tackle plus a mode where you can get a head-start based on your previous records, but again, not a lot of variety between runs aside from your builds. As long as you're okay with that, though, there's a pretty good chance you'll enjoy this one.
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47 of 59 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
20.9 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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