I've wanted a Mario paintball game for ages so how about that one Nintendo?
It could be first or third person, have really creative maps with pits, quick sand, traps and dynamic environments like mushrooms that you can jump on and bounce up higher to get a better view of where people are and where new items are. Items could include your standard star for invincibility, a boo suit for invisibility, a mushroom for burst fire and extra speed, Bomb-ombs that come in different colours and do different things such as slow them down with goop, blind them with paint etc
They could also have it so that players can move things like logs or bushes around the map and make cover or a base if it were a team mode so that there was some strategy involved that can't be found in many traditional shooters. You could even have things like goombas that you jump on to get more ammo or something.. Make a game out of the little things in shooters..
Would be quite the awesome sauce!
Essay Pro