So far, fun game.
Bug found: After playing a level again and doing worse than your previous run, the higher letter (i.e. A) will get replaced by a lower letter (i.e. C), although the high score still shows up.
The game does suffer performance issues in certain instances, usually at the beginning of the game.
I assume that getting 25000 Points reward an S Rank?
The Bonus Game is interesting, although seeing the ghosts is impossible when moving horizontally. Not sure if that was intended.
I do wish we have save slots. Accidentally pressing New Game could reset the game's save.