Mos Speedrun taps into a very pure vein of gaming: completing 2D levels as fast as you can whilst collecting as many coins as possible along the way. There's no plot setup, no dialogue, no character development - hell, you can only assume the main character is called Mo because of the title. Combining quaint pixel graphics with a vibrant chip-tune soundtrack, Mos Speedrun is a retro platformer designed with the touchscreen in mind.

Each of the game's 20 levels has four badges to earn: one for simply finishing the level, one for completing it in a certain time, one for collecting all the coins, and one for finding a hidden skull. Amass enough badges in each world, and you'll unlock the next batch of challenges. The stopwatch at the top of the screen only gives you a second or two of leeway before turning red and dashing your chances of a badge. With latter levels lasting anything up to three or four minutes, there's little room for error. You'll need to nail a more-or-less perfect run if you plan on beating the speedrun time, which requires that you know a level like the back of your hand.

There are no checkpoints. You either complete a level or you don't, which makes the game refreshingly taxing. After the first five levels the difficulty level soars, with enemies loitering around the exits of each jump, and spike pits restricting any extraneous movement. After each death, a ghost of your previous run will attempt the level alongside you, serving as a reminder of your past failures. This doesn't add anything to the core gameplay - you can't interact with them - but after attempting a level for the hundredth time, it's quite satisfying to watch a horde of doomed clones trotting along beside you.

For the most part, controls work fine - tap the right side of the screen to move right, the left to move left and both at once to jump. During the latter levels, however, where precise platform navigation is vital in making it to the end in one piece, I did find this somewhat finicky. Thankfully, there's a virtual D-Pad that can be switched to from the options menu, which makes things considerably easier.

It's a little on the short side, perhaps, but like all good iOS games, an update will probably fix that in the near future. That said, Game Centre support already offers a great incentive to replay, adding a full set of achievements and leaderboards, which are clearly a great fit for the time attack nature of the experience. It's a tidy little package, all in all - probably the closest thing the App Store has to Super Meat Boy, which is high praise indeed.