Rocket Bunnies has an interesting premise: You're a rabbit on a rocket (hence the name)...in space. There's no real story line, but your job is to ride your rocket across various galaxies, collecting all of the little bunnies that are stuck on various planets.
Each level starts out with your Rocket Bunny circling a planet. Using your finger and some timing skills, you must tap planets and guide your bunny across the universe. Various obstacles in your way--including mines, meteorites, and space-spiders--try to keep you from your goal. Sometimes you can avoid even going near these obstacles, but in later levels you'll need to perform some tricky maneuvers to get out alive.
To move from the planet you're currently circling to another planet, just tap the other planet. Your bunny will make its way to the other planet regardless of when you tap, but if you manage to tap the other planet while you're bunny is in the "acceleration zone," you'll get there faster. Timing is key, and the faster you can complete the level (by collecting all of the stranded bunnies), the more stars you'll earn.
Rocket Bunnies is a smooth game--the 3D-esque graphics looked excellent on my Droid X's screen, and the controls were responsive. Because the game uses a star system for unlocking galaxies and levels, lengthier levels can be frustrating. You need to earn a certain number of stars to unlock each galaxy, but many of the 60+ levels are just long enough that starting over multiple times (because you've become "space junk") is a chore.
Still, Rocket Bunnies is a fun, well-designed game with lots of free content. The bunny character is sort of grotesquely cute, with big buck teeth and bulging eyes. If you're looking for a challenging free game, check this one out--it's unlike anything you've ever played.