I'm thinking about a 2 player 2D arena game for a mobile phone, but I have the obvious problem of gripping. To avoid this, I think it shouldn't be a problem to play one in front of the other with touchscreen controls. The problem is, of course, the perspective of the sprites in the screen so they look okay to both players.
I'm thinking fully orthogonal perspective, but it hurts visibility a lot, specially if using human sprites viewed from the top of the head. Is there any example of a game that did this right?