Tumbler is an innovatice game in the way that it utilizes two mice to control an object (the green bar) so that it allows to people to collaborate on a mutual task.
The goal of the game mode demonstrated in this movie is to prevent a number of bricks from falling to the ground and breaking. To achieve this goal, players will have to move their mouse to influence the position of the bar, which is based on the average of both mice-pointers. Also, while the game progresses, the speed of falling bricks is increasing and more random and the bricks that have been caught so far influence the horizontal balance of the bar.
Possible improvements could be made, such as adding a Tetris-like way of clearing the bar (by lining up bricks) or extra feedback on balance (possibly by showing arrows/force vectors).