iO is an abstract physics platformer about size and speed. Grow bigger and smaller in order to solve some of the trickiest puzzles. Reach the exit as quickly as possible and grab a gold medal as your reward!
User reviews:
Very Positive (127 reviews) - 86% of the 127 user reviews for this game are positive.
Release Date: Dec 5, 2014

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“A highly addictive brain challenging game that will make you feel smarter as you finish each stage.”
4,5/5 – Gaming Cypher

“iO provides an entertaining romp that’s sure to test both your reflexes and brain power.”
Addictive – True PC Gaming

“iO is a smart physics puzzler that requires brainpower and a lot of trial and error.”
Smart – IGN Benelux

Dual thumbstick action

Just Updated

iO is back, bigger and better than ever!

At then end of this week iO will get a huge update. This update includes a big facelift for the game, a lot of new content, a few new mechanics and an extra hard challenge. And all of it will be FREE.

Here is the entire Update in bullet points:
  • 75 new levels: the Irrisitiball Levels. This includes ‘the Impossiball Level Pack’. An extra tough set of levels with fiendishly difficult challenges.
  • Visual enhancements, including background star particles, line shaders, spotlight glow, death animation and speed up sparks.
  • Price drop to €4.99 / $4.99.
  • New mechanics like moving platforms and bicycles.
  • Added instant level restart for controllers.
  • Fixed mutliple level bugs and glitches.

About This Game

iO is a physics platformer in which you control a ball. By growing or shrinking the ball you can influence its speed and weight. Use these mechanics to gain momentum and make your way through the levels. Toy with the laws of physics, solve the puzzles and reach the exit as quickly as possible. Can you win the gold medal in all levels?


  • 225 challenging levels to solve, including the extra tough Impossiball Levels.
  • Crafty mechanics like inversed gravity, portals, tricycles and movable objects.
  • Leaderboards in all levels to race against your friends and other iO players.
  • Bronze, Silver and Gold medals to earn.
  • Dual Stick controller support.

System Requirements

Mac OS X
SteamOS + Linux
    • OS: Windows XP+
    • Memory: 2 GB RAM
    • Graphics: DX9 (shader model 2.0) capabilities
    • DirectX: Version 9.0
    • Storage: 250 MB available space
    • OS: Windows XP+
    • Memory: 2 GB RAM
    • Graphics: DX9 (shader model 2.0) capabilities
    • DirectX: Version 9.0
    • Storage: 500 MB available space
    • OS: OS X 10.6+
    • Memory: 2 GB RAM
    • Graphics: DX9 (shader model 2.0) capabilities
    • Storage: 250 MB available space
    • OS: OS X 10.6+
    • Memory: 2 GB RAM
    • Graphics: DX9 (shader model 2.0) capabilities
    • Storage: 500 MB available space
    • OS: Ubuntu 10.10+
    • Memory: 2 GB RAM
    • Graphics: DX9 (shader model 2.0) capabilities
    • Storage: 250 MB available space
    • OS: Ubuntu 10.10+
    • Memory: 2 GB RAM
    • Graphics: DX9 (shader model 2.0) capabilities
    • Storage: 500 MB available space
Customer reviews
Customer Review system updated Sept. 2016! Learn more
Very Positive (127 reviews)
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89 reviews match the filters above ( Very Positive)
Most Helpful Reviews  Overall
68 of 76 people (89%) found this review helpful
9.6 hrs on record
Posted: June 7, 2015
UPDATE: New levels are insane!

Learn how to spin! This is one of this games that are easy to play but harder to master. You control a wheel, it can spin left and right or change its size. The bigger it is... the faster it falls. The strongest + in here is the levels design itself, they are unique and fun to play. There are many tricky moments also, so in order to complete them you must try different strategies (sometimes there are several ways to finish them). If you are stuck there is possibility to try different level because you can skip them. 160 levels included + additional 75 will be released soon.
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52 of 59 people (88%) found this review helpful
2 people found this review funny
4.8 hrs on record
Posted: December 5, 2014
The sharp, minimalist visuals of iO were the first thing that caught my attention when I checked out the Steam Store page. Having seen and played tons of puzzle platformer games I was asking myself if this game would introduce me to new gameplay mechanics I hadn’t witnessed or experienced before. And while we’ve certainly seen specific parts of it before in other games it does actually give us something new, and maybe even something to get excited about.

Having debuted on Ouya (a platform that everyone was excited about when it was first showcased, but once released the interest in it took a nosedive) iO never got the attention that it initially deserved. With the PC release it might still have a hard time getting any attention at all. So many games are released every week that it’s hard to get your game promoted, especially if you’re a small game developer. And it’s especially hard if it’s a fun game as well. Let there be no doubt: this is a fun game and I hope it does well, both commercially and critically.
The setup is simple: get the ball to the end of the level, marked with a portal. The levels are made up of random platforms, these can be horizon and vertical, as well as diagonal. Then there are the platforms that have to be pushed out of the way and tricycles that can get you across fiery (red) platforms that will destroy your ball. Falling down or getting too high up will also destroy your ball. It’s your goal to keep the ball on or between the platforms as much as you can.
But it’s not as simple as getting from A to B. Like a wise man once said; it’s the journey that’s important. And that’s exactly right. That’s because the ball has to increase or decrease in size to get through specific parts of a level. And within a few minutes you’ll learn how to speed up your ball to get to higher parts of a level but you’ll also learn how to blast off so you can jump across a gap. Not only that, but you’ll also learn how to jump, which is actually quite easy once you know exactly what to do (which is usually the case with pretty much anything these days). The keyword is ‘momentum’ which means you have to time your actions. You’ll be repeating levels over and over again because 1) you didn’t know what to do, or 2) because your timing was off. It’s usually 2) that causes the retry.
There are 150 levels to complete and each one you complete can earn you a medal. Can, because taking too long won’t earn you anything but if can complete a level within several seconds or minutes (this, of course, depends on the level) you might be able to earn a bronze, silver or gold medal. The gold medal usually requires perfection. You might not notice this right from the start, but halfway through things can get hard and earning that gold medal might not be so easy anymore.
The controls are easy; a controller works best here but bringing up the menu while in-game can be troublesome. I frequently pushed B to bring up the menu, but because the game wasn’t as responsive in this area as it should be it usually took a little longer. By then I was already rotating the stick and eventually was returned to the main menu or the next level. A small nitpick but still a little flaw in my book.

Graphics & Audio
As I already mentioned in the first paragraph the game uses a minimalist look, meaning everything has a basic shape and there are no backgrounds or background colors. It also uses basic, neon-like, colors like red and blue. It looks pretty in motion and the core of the ball becomes fierier the faster it goes. A little detail that doesn’t add anything to the game itself, but it surely looks cool.
Audio-wise it’s also very minimalist with some decent background music and basic sounds.

You can play this game just for the bronze medals or you can try to finish them all with gold. In any case it should take around 5-7 hours for a quick ‘playthrough’ and for a thorough playthrough it will take you probably double that amount. That’s plenty of gameplay for a game with this price.

iO (still) is a very fun, but sometimes extremely challenging, game that mixes up the genre a tiny bit. Its gameplay mechanics are solid, as are the controls, and its visuals are beautiful and relaxing. If you like to play puzzle platformers then iO is the perfect game for you. Even newcomers to the genre should have a bloody good time with it.
It was a small success on Ouya, but now is the time to make it an even bigger success. Click that ‘Buy’ button, people.

[Rating: 80/100]
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36 of 37 people (97%) found this review helpful
3 people found this review funny
16.9 hrs on record
Posted: December 18, 2014
Imagine a game where the character is just a ball the whole time. A ball that isn't even bouncy and can't jump. Consider how difficult it is to implement any platforming that isn't simply clunky and awkward with such a limitation.
Now let's think about 99% of platformers. How very annoying and limited would they be if they didn't allow changing directions in midair? It is completely unrealistic, yet omnipresent.

I thought about these concepts a lot, and didn't believe it was possible to make a decent game with the mentioned limitations. And yet, here we have iO, and calling it decent would be a huge understatement.

So yes, the character is a ball that can roll clockwise and CCW. You don't simply "move right"; the movement happens because of friction. The ball can also shrink and grow (changing its mass) anytime. Arbitrarily changing mass and angular momentum are the only unrealistic things here; the rest is just physics.

And oh how fun pure physics can be...
As mentioned, rotating allows you to move using friction. The friction also applies to walls and ceilings, allowing you to do not-so-obvious things. Changing mass in mid-air while keeping the momentum lets you change the trajectory (launch yourself). The process of growing in size improves your grip, letting you speed up easier, or... climb some walls! Now, don't forget that you can only grow/shrink so much...
And of course, we also get the more typical features of a physics-based game: There are moving platforms. You can push and interact with things in other ways using friction. Portals: speedy things comes in, speedy thing comes out... but what if the thing can change mass?

The game is almost flawless (if you overlook occasional clipping through objects in rare cases, which doesn't affect the gameplay).
Graphics are very aesthetically pleasing. Won't talk about music, because I rolled with my own.

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28 of 35 people (80%) found this review helpful
2 people found this review funny
0.9 hrs on record
Posted: January 9, 2015
Physics based puzzle platformer from Gamious. Definitely one of those simple to play yet difficult to master games.
With a 150+ levels, responsive controls and a relaxing soundtrack, if you enjoy the genre it should keep you going for a while and recommended. :]
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21 of 23 people (91%) found this review helpful
2 people found this review funny
2.1 hrs on record
Posted: December 5, 2014
After playing the game for about an hour, I can definitely say it's worth buying! The game features O, a small ball which has the ability to get bigger and get smaller. By doing so you increase/decrease your mass, alowing you to gain a lot of momentum when being big, and then transforming that momentum in actual kinetic energy when your smaller. Obviously the game has way too many features for me to discuss right now, so I'll just write down the tops and tips.

-Very good graphic design for a game of this genre
-Non-lineair gameplay, so that the game stays fun
-Good music
-Runs very smoothly
-Plenty of content (150 LEVELS, HOLY SH!T!!)

-Perhaps implement a competitive leaderboard (I haven't seen yet, might have missed it) so people can compare their score to others
-Implement multiplayer
-A level editor would be awesome

I definitely recommend you to buy the game, as far as I've seen. If you want to watch some gameplay first, check this video:

I rate 8/10, simply a great game.
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16 of 19 people (84%) found this review helpful
2 people found this review funny
1.2 hrs on record
Posted: December 5, 2014
iO is a clever little game with simplistic and very addictive gameplay.
The goal is to get the ball into the portal. Sounds simple enough on paper, in reality its pretty tricky. You can change your size and that will determine your speed and the rate at which you gain speed, and this is essential part of the gameplay - figuring out the optimal size to achieve a task. There is no time limit on the levels ( all 150 of them !!), but medals are awarded, depending on your speed of completion - the faster, the better. About that, I would love to see a timer inside the level, but maybe that's just me.
The controls are fine, I used keyboard - either WASD or the arrows. The ability to rebind tjem would be a plus, but I didn't feel the need for it at all. The music is abstract and fitting, the sound effects are not that much, but still reasonable.
There is no level progression, you can start from whatever level (out of the 150) you want. There is a trial pack of levels, that plays the role of the tutorial and introduces you to the game mechanics. After that, there are still the occasional hints inside the first few levels, but the game does not hold your hand by any stretch of the imagination. After the first few straightforward levels, you'll need time to figure out the way to complete the level, and then actually execute your plan ;) It's enough to say, the game has a key to instantly reset the level - you will use it a LOT. The trial and error is the way to complete most of the levels for the first time. I really like the steam leaderboards and the ingame medals, as there is always a way to improve with these game mechanics ( it's not set in stone thing like a "jump" - you gradually change your size and speed, so optimal size and time to switch it, is hard to determine).
The only thing I dislike about the game is, that it has the nerve the actually spin up all my hard drives before starting - typical for a KISS release, and really annoying in my opinion.
With the pretty simplistic game graphics and mechanics, a level editor will be a really nice edition to the game at a later stage, allowing the community to go nuts, but for now, I think, trying to ace the 150 levels is more than enough.
The huge amount of levels, steam leaderboards, steam trading cards, addictive gameplay and that price tag ... all of it leads to my wholehearted recommendation of the game!

TL:DR you can check my overview video, where I complete the first level pack :
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11 of 11 people (100%) found this review helpful
5.5 hrs on record
Posted: August 2, 2015
A minimalistic puzzle platformer game where the main concept is the ability to shrink or grow your ball in order to navigate through the levels. Gameplay is fun and is broken into levels which gradually get tougher. The background music is very well done. Really easy game to learn but hard to master. Works well on keyboard+mouse or controller. Overall a very fun little abstract game to add to your collection.
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13 of 15 people (87%) found this review helpful
3 people found this review funny
13.8 hrs on record
Posted: February 11, 2015
Well since then the Recommand Percentage is still 100%, of course I won't destroy that
This is the 36th positive Steam review on this game

This is just a new game avilable for purchase on 5/12/2014, after playing it for an hour or more, I can tell you I love it. In the game, you play with a ball that just roll and's only "skill" is turning it own size. The first few levels are easy, but harder and me, this game is really hard to challenges your IQ...

There's one thing good about this game, if you are stuck on a level, you can chooce to skip it and try other levels first instead. So you won't get bored and annoyed:)

Personal Score: 8/10
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15 of 19 people (79%) found this review helpful
3 people found this review funny
163.0 hrs on record
Posted: December 16, 2014
Physics platformers, oh how I love breaking you.

Having tons of fun speedrunning this game - It has good physics - good strategies - mechanics/bugs/exploits to abuse - Leaderboards with me #1 on them... What more can I ask for <3

If you like solving puzzles - or have a competitive bone in your body defintely reccommend picking this up and challenging me. Goodluck.
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9 of 9 people (100%) found this review helpful
1 person found this review funny
4.7 hrs on record
Posted: March 1, 2015
Honestly I think of iO as kind of a TrackMania platformer!

Fun physics-based puzzle game with a minimalist design focusing on momentum, traction, and gravity. It can be a little tough at times but it’s definitely a unique twist on platform puzzlers and deserves much more attention than its gotten so far.
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Recently Posted
=iO= Sisyphus1985
8.1 hrs
Posted: July 31
i'll keep it short. Atomosphic and challenging yet very relaxing. One of my all time favourite games and soundtracks. Easily Worth more than $5.
Helpful? Yes No Funny
4.0 hrs
Posted: June 9
a simple and well made puzzle game, sometimes its best to keep things simple and with this game the developers have nailed a good and perfect time killing game. this is a must have game and for the price its a steal indeed.
Helpful? Yes No Funny
3.0 hrs
Posted: June 3
Product received for free
This game is great
Helpful? Yes No Funny
2.8 hrs
Posted: May 28
nice platformer with simple rules. the levels use physics to give it a lot of depth and keep the gameplay new.
Helpful? Yes No Funny
3.4 hrs
Posted: May 13
Good game, Pretty challenging, love the game 10/5
Helpful? Yes No Funny
2.9 hrs
Posted: April 12
Awesome game! great representation of physics and hard but just cant stop playing! :)
Helpful? Yes No Funny
0.4 hrs
Posted: February 26
Do YOU have an insatiable hunger for physics? No? Oh. ok...Never mind...

How about gold? do you like gold? Just silver? Well stop pooping on my parade and buy the damn game!

It's relaxing. It's rewarding. it's challenging. it's totally worth full price, even though I paid $1.25 for it :3
Helpful? Yes No Funny
11.1 hrs
Posted: February 7
Helpful? Yes No Funny
18.3 hrs
Posted: January 16
A very nice and well-made puzzle game which is both challenging and fun. You control a wheel and uses its ability to shrink and grow to climb walls, drive through loops and do many other cool tricks to guide your way through the level. You have 225 levels to go through and the difficulty increases for each stage. It's one of those games where you just replay the same level 100 times to get the best time as possible. And with the leaderboards to compare your times with other players, it makes you want to improve your time even more. For the price its at now, you'll get a fun and addicitive game that you will enjoy a lot.
Helpful? Yes No Funny
8.0 hrs
Posted: December 5, 2015
great game if you like skill games
Helpful? Yes No Funny