A cool game mechanic would be, when the screen warps the players near eachother if they could exchange items, or attack the other - or kite a monster through the warp at the other player... especially cool if you had to travel far away on the map from the other player to grab the monster to fling at your opponent (without being killed by monster) (or maybe you have to get to a BFG first and frag 'em... through running in opposite directions to your bfg base, ang fighting monsters, and flinging then through the warp until you reach the bfg, which is the only thing which can shoot through the warp...
your side arm is a gun and a tractor whip with a heavy cool down to entangle a monster to throw through the warp, so use it strategically. whomever gets to their bfg firt - now play it on a large square screen, with four players, one per quadrant running to the bfg and flinging monsters through the warps - the center picks a player at random when flung into.
There are so many Co-op / PVP scenarios I can think with this screen warping mechanic...
Puzzles that require you to go different directions, to gather components for the puzzle, but you have to first find the warp-thrower to transfer resources, which you have to gather and transfer to your warp partner to solve the puzzle, but you need that BFG to throw resources to the other.
Multiplayer maps where your maps are vastly different, but you have certain "tiles" that are all shared... when two of you run into the same tile - you are warped in multi.... and then you either have to fight or work together.
Some tiles can be "ok we are warped together: what are our goals? "Fight eachother|team against other guy|find a resource| trade| etc"
This mechanic can be so widely used....
I LOVE IT (BTW - I AM one of two of the guys that built the gaming marketing for Intel for proving that a <$1,000 Celeron Machine could satisfactorily play games such as DOOM, Descent, UO, etc.... I know a little bit about gaming. My cohort at intel is an EVP at gaming companies you have all impacted by) (I went tech, networking, medical, etc - he was all in on gaming)
A cool game mechanic would be, when the screen warps the players near eachother if they could exchange items, or attack the other - or kite a monster through the warp at the other player... especially cool if you had to travel far away on the map from the other player to grab the monster to fling at your opponent (without being killed by monster) (or maybe you have to get to a BFG first and frag 'em... through running in opposite directions to your bfg base, ang fighting monsters, and flinging then through the warp until you reach the bfg, which is the only thing which can shoot through the warp...
your side arm is a gun and a tractor whip with a heavy cool down to entangle a monster to throw through the warp, so use it strategically. whomever gets to their bfg firt - now play it on a large square screen, with four players, one per quadrant running to the bfg and flinging monsters through the warps - the center picks a player at random when flung into.