Wind-up Knight from Robot Invader is a unique and stylish side scrolling obstacle course action game. The game looks good and plays well, and it can be brutally difficult and challenging.
You play as a wind-up doll that also happens to be a knight. As you run through each level, you must collect new winding keys to keep your body from shutting down. As you play, you'll learn new and different functions and the levels evolve alongside you. You'll begin with a jump button, but quickly learn how to attack enemies, roll under obstacles, and shield yourself from falling objects. Each level is a set obstacle course with several coins and keys scattered about, as well as special hidden collectible cards. The game wouldn't be so difficult if they just gave you some checkpoints, but unfortunately, all levels must be done in a single run.
As you play, you'll accumulate a lot of in game money, or "notes." You can use these to buy new weapons and armor that will improve your chances of survival by augmenting your abilities in several ways. The game is fun, but it's pretty challenging, and you'll need very good timing to get through later levels. There are four worlds with over fifty levels total, with each world being represented by a big fantasy book.
The whole wind-up doll, "gears and cogs" aesthetic works well, and the game has a nice color palate, even if many levels are just a bit too dark. The soundtrack and effects are nice, and the game is very holistic in its theme. The game completely froze my Nexus One a couple times though, to the point that battery removal was necessary. I should think that kind of bug is very device specific, though. The game is listed as free, but only the first world comes free. The rest of the three worlds will cost either 1200 in-game notes, or a two dollar in-app purchase each to unlock. You'll also have the opportunity to unlock them all for a discounted four dollars, but it's a onetime offer. The game is well made and fun, and I recommend at least trying out the free levels.