KiKi is an intense little overhead-view shooter somewhat reminiscent of Last Alert in its "free roaming" style. It's the type of game you'll gradually feel yourself getting more and more awesome at as you put in practice. The later levels are quite challenging, as they present you with lots of projectiles and small, quick enemies to worry about in tight spaces.
The boss fights are also fairly difficult. It feels great to figure out effective methods for getting through them.