Held in prison for daring to protect his beloved from an attack, I Must Run!'s nameless protagonist is challenged to break out and run across the city in less than 24 hours for the ultimate prize: his wife's life.
Apparently the escape itself poses no problem, as we cut straight to the chase. I Must Run! is a game of the same ilk as the immensely popular Canabalt, a reflex-testing title that puts your hand to eye co-ordination and parkour skills to task. Constantly pressing forward at increasing pace, you've got to avoid any obstacles in your way as you leap from rooftop to rooftop towards your goal.
I Must Run! sets itself apart from similar titles by bumping up the complexity slightly, adding further actions to use in different situations. Hopping over gaps is not your only concern; you've also got to punch away or jump over hazards, such as flammable barrels or pesky pipes, and slide under any low-jutting ceilings. You can also double jump to help recover if you've misjudged a move.
The random nature of level generation means that you can't rote learn stages or get lax; you've got to keep your eyes peeled for any problems and hit the appropriate button. Each action is mapped to both D-pad and face buttons simultaneously, and the inputs can be mixed and matched at any time. Whether you want to use Down to slide alongside X and A to jump and punch respectively, or perform all actions with one or the other, it's all good. Unlike the iOS version, there's no touch input in the DSiWare release – which works for us, as buttons often do the trick best in reaction reliant games anyhow.
Unlike many in the genre, I Must Run! is actually linear and completable. That doesn't mean that you'll be able to easily, though – it's as hard as nails. There are six levels, taking the ridiculously healthy man sprinting over jail buildings, skipping between trains in a subway, precariously darting over girder-filled construction sites and more. Each is filled with busy, multi-layered backgrounds that feature changing weather, helicopters, swinging cranes and other things designed mainly to distract you. The blockades you come up against alter from stage to stage, each adding new elements such as longer areas to slide under or raised segments of platform to traverse.
Even the first stage is tough and threatens to tear at your measly four lives, which rapidly deplete without proper concentration and decent reflexes. The main reason for the difficulty is the length of each area. Dying means you're plopped back at the beginning of whichever level you've reached, these changes of environment being the only checkpoints. To forego failure, you can't make a single mistake – and the problem some will have is that levels can last around two and a half minutes. It doesn't sound like a huge amount of time, but with the ever-quickening speed and absolute perfection demanded, it's not for the weak of knees. You're going to need lightning thumbs and the patience of a saint to master it.
It takes some practice to get used to the pacing too. When moving slowly it's a bit too easy to fall down a pit to your doom without the necessary momentum behind you, and it's only when you pick up speed that it starts to feel right. That doesn't take too long to build up, and the double jump compensates for it when you're trudging along initially, but it isn't quite as instantly accessible as was perhaps desired.
If that story mode isn't for you, fear not – you can still experience all the levels in the endless mode that jogs more closely to its genre-mates. Here you just need to keep ducking and diving for as long as physically possible to set the most amazing records. The drawback is the lack of online functionality, which means you can't upload your best distances for the world to coo over, somewhat taking the wind out of this mode's sails. In a similar vein, in either game type you can collect points for getting jumps just right – landing impeccably on the edge of a ledge – or punching dangers out of the way rather than vaulting over them – but there's no real reason to shoot for high scores, as there's nowhere to share them.
I Must Run! is a challenging but nonetheless entertaining entry into the 'runner' genre, and while its linear storyline isn't going to be for everybody due to its high demands, that's not all it has to offer. The endless mode is just as tough but leaves out the lives and set level lengths so that you can focus on beating your own distances and times alone, though lack of online leaderboard support is disappointing and undermines its potential.