Have to add, Bomberman is great. Play this frequently with a nearly 5 year old boy I nanny. It's works as single player, or as multi-player using multiple GBA's.
I've only played it in Battle mode, where the aim of the game is to blow up your opponents. It's not really a shoot them up, it's hard to describe what it is... it helps children (and adults) use logic... you have to think before you place your bomb, or you can blow up yourself!
Link to a Review: www.tendogamers.com/reviews/gba/0016.shtml
Nick