Things I liked:
-movement was smooth.
-sound effects were great.
-Creepy thing I didn't even know was in the game before it was too late.
Things I would have changed:
-The blinking lights, they are a nice touch but a bit jarring to look at the whole game, I would try to increase the minimum flicker to keep the same effect, but less stress to your eyes.
-The repeating screaming (which might come from that creepy thing I found) was looping a bit much for me. if it was more spaced out it would really creep the player out because you never know when its going to make that sound.
-Gems, I would have placed a gem right in front of the player at the start. It would let them know what they are trying to find. also maybe a max gem amount, the maze is large there is no way of knowing how many there really are, leading to some unnecessary back tracking.
Over All: loved it! Great work!