I highly recomend Puyo Pop fever for multiplayer. In fact, I don't believe I've played more than five minutes of single player and I've easily racked up hours on that game. Whilst it's a bit like tetris, in that stuff falls from the sky, I think the competitive element is far greater.
And when I say competitive, I mean 'Bastardly' element. When you get lines in tetris, they come up at the bottom of the other person's screen, which is a bother, but doesn't effect what they were doing at that moment. But in puyo pop, the equivelent of lines (in this case groups of four coloured beans) falls on *top* of, often ruining that mega chain of 5 or 6 beans you were just about to have. It's beautifully agrivating
