"Once you manage to complete all the stages, you can then either take on various challenges which require you to fulfil certain objectives, varying from clearing all the pegs in a level to amassing a certain amount of points. Or you can play a Duel against the computer or a friend. Although Peggle is a strictly casual title, that doesn't mean that it's best enjoyed in small bursts. The first time I picked it up I played through the whole of adventure mode without a break.
It's worth pointing out that if you do get the Iphone version that the graphics are a little worse which is disappointing given the potential of the Iphone as a platform. Peggle plays a lot better with a mouse, still it's one of the better options in the Iphone store and it offers as much playtime and fun as many games with bigger production values. A recently announced Xbox 360 port should also ensure that there's always someone to play a Duel against too."