visually really consistent and the audio ambiance sets a good tone. i like the concept and the levels are ordered well in increasing difficulty.
my largest issue was that i wasn't certain when i had reached the end. the room shown in the preview image is where i ended up and i think that was the ending of the game? the only suggestion i would have for game mechanics is to display the key you dropped on the panel itself (in case people forget what key they left where).
otherwise encountered no bugs and found the solution to every level after a decent bit of thought! nice work