Looks great, and the atmosphere is good, too. I wish that the entities were a little faster, and that when one entity was destroyed it immediately gave game over, as there is no longer a way to defeat enemies (apologies if one of the entities does respawn, but when I played I just immediately let the enemies kill my remaining entity so I could restart).
Overall pleasant experience, good job. I agree with DancingEngie, a motivation to get the player to move would be good.
If you do get a chance, please check out my game! :)