-the level design is really genius.
-Music is Ok-only way i reached the level 12 is by turning the sound off(just my game-play style) and the game art is well suited for this game.
I reached the level 12 maybe - i forgot counting but it was the third screenshot picture of this game where there are 4 portal. and that was too hard to control. Would be easy to play , if the player's collision detection area is little bit smaller than its sprite size.
the key to play this game is to control the opposite direction key.
Overall, this game is really good and enjoyed a lot. Would have bought it if it was on mobile platform oriented game. Good job, well made!