I'd suggest removing the two "surprise" spikes where my character is above here. They seem to be unnecessary, though I'm not sure if this is to prevent the player from going to the right (which they can do anyway once they land on the thinner platforms).
That aside, this was a really enjoyable, simple, but challenging platformer. I thought the moving platforms were interesting and the most memorable part of the game. The music is great; it's got an intensity perfect for the challenging rooms. The sound effects are also well done, love the walking and key collection sfx in particular. I look forward to seeing more levels; perhaps, in the future, you could also consider a map?