Visually nice looking game, I do think it could use a few improvements with the gameplay however.
The enemies in the game move the same speed as the player, which makes it hard to escape them if you need to regain your health. The bullets however move faster than the player, making them even harder to avoid, especially when the screen is cluttered.The game could also use some sound effect or music in it, but I've seen your other comment about that, and it's entirely fair as to why they're not included.
I liked how the game's title screen was readable and concise, and explained both the controls and objective to the player.
It was a really good attempt, well done!