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 (28 reviews)
Release Date: Oct 1, 2012
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Recommended By Curators

"Probability 0 is a roguelike-like similar to Spelunky, in which you keep venturing downwards until your inevitable demise."
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

    • 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
45 of 55 people (82%) found this review helpful
6.9 hrs on record
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.
Posted: June 13
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12 of 14 people (86%) found this review helpful
1.7 hrs on record
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.
Posted: June 13
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12 of 16 people (75%) found this review helpful
3.4 hrs on record
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:
Posted: June 18
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3 of 3 people (100%) found this review helpful
10.8 hrs on record
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.
Posted: June 23
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6 of 9 people (67%) found this review helpful
1.0 hrs on record
Like a streamlined Spelunky, great "fun-to-die" game. Highly recommended.

Posted: June 13
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