Press Buttons, Change Sizes in Co-Op Puzzle Platformer Shift Happens
Here's the pitch: you're an ambulatory mound of jelly, see, and your partner is also an ambulatory mound of jelly. You can both change sizes, but whenever one character changes mass, he adds/removes mass from the other. Sounds like boring science stuff, but really it's Shift Happens, a couch co-op puzzle platformer just released on Steam Early Access by Klonk Games.