Really creative mechanics and comfortable graphics. The idea of jumping into the water(?) and going back to the birth point without resetting the game is amazing. Somehow stuck at the level where the inverse button appears for the first time until I saw your hint to a previous comment.
Besides, I think it would be better if pressing WASD directly moves the character instead of turning the character to that direction first and only moves when you hit the same key again (unless you're planning to make puzzles related to the direction of the character).
A small bug: it seems that after hitting the spacebar to start the game, you can't move or eject unless you press P and restart the first level.