Snails Reloaded, a Worms clone, was pretty good for this...but seeing as the real Worms is on the way I'd probably hold out on this one
SlotZ Racer has simultaneous multiplayer, as does tap tap. SlotZ is a great game but the multiplayer doesn't always work so well, because the track gets really zoomed out.
world cup ping pong and world cup air hockey are my guilty pleasures. i can only get them to run 3 out of 5 times but, when they do, my fiance and i have loads of fun playing them. another game i play with my fiance is lightbike.
Lightbike is awesome on one iPhone, and, if you have two systems and are on a wi-fi network, you can play up to four player.
space ninja, although with multiplayer it becomes somewhat of a racing game. iShoot and UniWar I wish Galcon could be played with two people on the same phone/pod
thinkin of gettin worldcup pingpong, worms gettin that for sure when it comes out. gonna download air hockey today, got knots & dots from the suggestion earlier (thank u) , have slot racerz & tap tap 2 already - any other must have 2 player on same iphone games?
2 player galcon is technically possible but it wouldn't play very well. The game is real time so it ends up being a fight over who can keep their hand over most of the screen, haha. Galcon was made to handle 32 simultaneous inputs even though the iphone itself will only allow 5. So if the hardware allowed it, and the screen size was increased, 2 player could happen. Try rotating the game into landscape mode and playing a campaign game with a friend. Just take another planet on one side of the screen. They handle the left side and you handle the right side. It gets pretty interesting and you need to coordinate moves against the harder AI
you could do galcon on that giant touch screen that sway and touchgrind was on. that would be so cool.
Robot Wars - 2 player fps on same device Lightbike ****** (Edit: Why is it blocking out b o w m a n as one word?) Slotz
That's weird. There is a free version of B o w m a n that is called Archers. It has a bit more polish and is very fun. Robot wars looked interesting too.