Though racers are a natural for a device with an accelerometer and no physical controls. Their drawback is how they handle speed. Tilting the device forward fundamentally alters your viewing angle, making fast-twitch reactions difficult for newcomers.
Ion Racer (99 cents, iOS devices) a futruristic race game taking cues from WipEout, shrewdly avoids this problem while still setting a stout challenge with plenty of incentive to keep trying against it.
Rather than serve complex maps, Ion Racer sets you on a mostly straight-ahead endless course (with some turns). Speed is governed by how many "Kions" you acquire, the glowing orbs that mark your optimal path down the course. The twitch comes in acquiring energy, power-ups, health (or ship repair) and avoiding obstacles that can damage you.
Red barriers are your biggest enemy; they damage you but can be broken down with a weapon called "Strike." There's another called "Focus" which slows down the action, but not enough that I really used it. Strike was my go-to.
These variables and objectives combine to form a near-endless series of race challenges: Acquire this many Kions, use your Strike or Focus this many times, survive for this long on the course.
The best part is that you don't have to satisfy all of the objectives in one run. The game would be brutally difficult if so. Your progression is cumulative, so a huge points-gathering run that fell short of some other goal isn't wasted. It allows you to strategically focus on the toughest goal first while returning to the easier parts later.
Well illustrated and fun, Ion Racer is a compact, pick-up-and-play racing challenge that's easily recommendable.
Ion Racer [iTunes—$0.99]