Goin' full Gameboy is certainly novel! The core mechanic of only being aware of one enemy at a time is a great use of the game's theme, and the core way the game plays fits that well. We wish that there were tighter corridors for the enemy to come down, though; since they can come from anywhere, and through walls, we didn't really form a strategy. Trying to play by flipping between ghosts and popping them as they come is only somewhat more effective than spinning in a circle and shooting.
This was a charming game, and it's nice to hear that you were able to round it out! Only caught a teensy bit of you streaming its development.