This is a really cool mechanic! I don't think I've ever played a game where I had to move _away_ from something to trigger it. It made me have to think in a new way, and that was fun!
My only real criticism would be that the controls are a little awkward. I wish I could hold a key to keep moving in a direction, plus having Enter and Space not be a confirm key was unintuitive.
Still, a nice idea!