Nice work! its always a challenge to make a game and putting rules and limitations in the mix never makes it any easier. You did a great job making the art feel like a game boy game might. One thing I felt could have used some polish was how the player feels like it "gets stuck" on the wall. Like if you are holding right on the controls and you hit a wall and press up without releasing right the player doesn't move up, or at all. If the player "slid" along the wall upward in this situation then that would would feel better to me. Its crazy how such a minor thing effected my gameplay so much, causing me to not get very far, so unfortunately I didn't get to reach the stealth aspects of the game.
I liked the excitement and spooky nature of the game! you did a great job using the theme for inspiration!
The art is well done and feels like something similar to what you can find in actual game boy games.