In the game Ninjae*, you control two ninjas: Red Ninja and Blue Ninja. The two are hellbent on killing each other, but right now, they need the help of each other and you to defeat the obstacles in their way.
Blue Ninja experiences, after an uncomfortable accident in his childhood, reverse gravity. This enables him to run in the ceiling, but leaves him unable to walk on a decent floor. Use this to your advantage.
Sadly, we did not manage to finish this game on time. :(
*The word ninjae is the plural of ninja, in the same way that antennae is the plural of antenna.