[moron4hire]

This is why I love the level completion replay from Super Meat Boy. It plays all of your previous attempts, superimposed in real-time.

I always thought it'd be really crazy if you could play with all those ghost images in action and there was collision detection with them. So all those "particle" meat boys would be interacting with each other and maybe create some wave diffraction patterns.

[tumey]

Sounds like Super Time Force, where your previous attempts remain and assist future attempts.

https://m.youtube.com/watch?v=zrYrd1AuQR0

[diegoperini]

"Braid" has that kind of collision.

[krallja]

Does Not Commute, by Mediocre AB, is a fun mobile game that plays with this concept.