Thanks for the feedback. I'll definitely be taking those suggestions on board when I make a more elaborate version of this. The sound was a last minute (well, last morning) and I didn't even think to synchronise it with the animation. And a turn is definitely something I think would look cool - if I can make it work with the 4-direction art I have for the robot. If I can, I want the enemies to occasionally stop and look around so there's a lot of room for improvement.
The light thing was a pain, especially as I couldn't use Godot lighting in compatible mode. Ended up with a solution that builds a complex shape from ray casting and using collisions to mask it.