That was cool! The art is proficient and the character designs are charming; I especially like the ghosts! The soundtrack is also great; it fits the gothic atmosphere and setting.
The mechanics are competent, but awkward and poorly balanced. I agree with everything Nikoichu said below regarding that.
The audio balance is a bit off; the sound effects are much louder than the music.
Whenever I used the Reveal, the main screen rapidly flashed inverted colors a few times in less than half a second. Is that supposed to happen, or is it a bug? If it isn't a bug, it warrants a flashing lights warning. (It also breaks the four color restriction, but that's less important than the flashing lights.)
All-in-all, good work! Congratulations on making the game from scratch!