If I understood it right, let's say your pieces fall from top to bottom and mine from bottom to top. And when our pieces collide they stop. But what happens if they don't collide? What if I avoid your piece and sneak past? What happens when my piece reaches the top or yours the bottom? Would that mean the end of the game? Because if it would, then the game could degenerate into a race towards instant game over and I don't know if that would be fun.