Cave story

I like this game, its an adventure/action/platformer 2D game.

"Cave Story is a freeware sidescrolling action/adventure/platformer title with leanings towards Wonderboy and recent sidescrolling Castlevania titles. You control a little amnesiac who runs around helping out these rabbit-ish creatures called Mimigas while trying to find your way out of the giant cave inside the floating island which makes up the game's setting."

The game is initialy in japanese but people made different translation : English, Spanish, Chinese, Portugese, French. And you can play it on different plateform : Windows, Mac, Linux, Nintendo DS, PSP...