Good:
- Music and sound effects are really nice
- Uses the rewind theme well
- Nice concept of having to get upgrades to stop yourself from becoming too weak
Could improve:
- I sometimes got stuck on a corner while moving, maybe wall collisions could be improved
- Displaying health of enemies
- Displaying player health above the player
- Make it more clear what stats are decreasing each round. I wasn't entirely sure what was changing between levels other that the number of bullets I was firing
- The energy particles sometimes got stuck in the corners and I couldn't get them
- Particle effects for shooting and landing shots would make the game look a lot more polished
- Maybe checkpoints? Depends on how hard you want to make the game
Overall a fun game :D