your suggestions are right, we missed the "Polish State" of the game, adding particles and sound effects would have made the game more better for the eye and ear.
levels were the most thing we didn't give any time (because we didn't have time xD) a lot of ideas we had in mind like more functions for the box or more enemies, a boss and of course more benefits for the key and door idea.
and god willing we will do all of this stuff in the new update, Thanks so much <3 (can't believe you played our game T-T)