CASCATA is a game with empathy built right into the mechanics. Everything you do will be for the person you're playing with, whether its collecting diamonds to destroy blocks bearing down on them, or giving them hearts to prevent a game over. I wanted to make a game that necessitated being your partners' keeper, and not just looking out for yourself.
There's also a 1 player mode where the role of two players is placed on you. You must avoid blocks but also not let them touch the bottom of the screen, or else its game over.