Dont worry, you can save the game and continue from saved position next time. You need to guide Jak through dangerous world, and help him to save his friend. You will be threatened by many enemies along the way.
This game is huge and you will need lots of time to complete it.
GameCanvas is a Canvas with additional capabilities; it provides methods for immediate painting and for examining the state of the device keys. These new methods make it possible to enclose all of a game's functionality in a single loop, under control of a single thread. To see why this is attractive, think about how you would implement a typical game using Canvas: