Trine is much like a story tale, it's set in fantasy medieval times and follows the adventure of a Warrior, Thief and a Wizard who both find a magical object and are linked together to help save the kingdom from destruction.

The game is a physical (Has PhysX capability) platformer with FANTASTIC graphics and music (Although, don't expect anything Crysis for the graphics). It does have multiplayer, although only on 1 computer (No LAN or Internet) and has no addon support.

Trine 2 is meant to be coming out in Spring (For Northern Hemisphere) and has ONLINE Co-Op

2D or 3D platformer (or halfway in between?) This sounds like fun, I'll have to check it out for PC. I don't think I've ever heard previously of a platformer with online multiplayer.

half way. Everything is 3D but you can only Up, down, left and right (like LittleBigPlanet, although you can go back and forward in that)