I absolutely love the aesthetic of this game's art style! The lighting, colors, and textures work very well together. I also appreciated how smooth the gameplay felt. It was very fun to whiz around the level and strafe around enemies. I could see myself playing this over and over for a long time without getting bored.
As others have mentioned, I also felt the insta-kill projectiles were a bit too punishing, especially since I didn't encounter any checkpoints. Implementing a rewind function is very creative, but I wish you didn't restart at the beginning of the level every time. I also felt that the default movement was a bit too sensitive, but a mouse sensitivity option could easily remedy this.
Great work!