Right now the programmers' team has started to work at the player code. We'll have two players and only one of them will be able to switch the gravity by double jumping. I agree that we shouldn't make the things too complex; 180 degrees gravity switching should be enough, at least for now. At this point I think that only the player should react to the gravity switch; we'll probably add light and heavy boxes that fall down to the floor / raise up in the air when they aren't blocked by other obstacles.

We are trying to come up with a quick prototype and see how fun that is to play, and then we'll decide on the following steps. We'll probably post the link to it here and see what you guys think about it.