Though it's advertised as a co-op game for 2 players I was pleasantly suprised to find out I can in fact play this game with unlimited people on a single controller! 
On a serious note: There's a bug where the game will only display a black screen if no controllers are connected, until you connect a controller after which it spawns a player on runtime. And this loop can be repeated for as long as you like (I only tried 5 times, but I don't see why it wouldn't be infinite).
The black screen was a bit confusing though, as the keyboard still works and creates sounds.