several years ago (maybe a decade?), I played a really good freeware game about time travel.

You played a robot, and you had to collaborate with yourself to solve puzzles.

Before anyone suggests it: t's NOT Chronotron!

* The robot you play has tank treads
* The art is all in a hand-drawn style
* I think there was a song at the end of the game

If anyone knows what this game was called, let me know!