Thanks for the feedback, and for the Godot suggestion!
The fact that you can push the boulder back wasn't actually intended. I originally made a push area that only allowed pushing it to the right, cause the idea was that the player should always throw it into the void (other side of mountain). Unfortunately, i ran out of time before i could add the tutorial and story that explained why this was the intended behavior.
The story was supposed to be that, after Sisyphus throws the boulder over the mountain, it almost hits a woman. Since the game takes place many years later, stones have become scarce, so she starts collecting them and eventually helps Sisyphus automate the process. Zeus should eventually notice something was wrong, and the story would continue from there.
I honestly like this concept a lot, so i definitely want to revisit it once i've gained more experience from other small projects