Buka is an avoidance Asteroids-like game adapted for a touchscreen interface. By clicking and dragging, you can move the eponymous blue circle out harm's way as a variety of colorful "baddies" come hurtling towards him. You can also click quickly outside of Buka to deflect nearby objects, or click, hold, and release to cause a small explosion that will destroy or fragment most asteroids (and provoke the ire of others!)
There are two game modes: Journey, in which Buka progresses through numerous waves of enemies on his way to "the happy place," and Survival, in which you simply keep it alive as long as possible. It has health which can be depleted in about five hits, but which can also be restored with interception of the occasional glowing green shapes that emerge from destroyed asteroids. Larger asteroids also produce fragments when destroyed, which are just as dangerous to Buka's health.
Sam's Protip: Explode twice over large asteroids to get rid of all the fragments at once, thereby saving yourself a bullet-hell-like avoidance situation.