Great game! I liked the concept of powerups being hidden until you're near them, it makes it so you have to explore the map. The health bar seemed like it didn't show the correct amount of health. I could pick up a heart and it didn't fill up or take damage when it was empty and didn't die. Also, I feel like the AI bullets should be a little slower to dodge them easier as they're the same speed as the player's bullets.
Good game though and I enjoyed exploring the map.