Visually, I think it's gorgeous, a real pleasure for the eyes. The audio adds a lot to the game, too. This is a simple idea that's really well executed, great job!
The fact that the enemies are able to shoot behind them makes thing very difficult fast, because you have to evade while moving forward, potentially running into an enemy that just spawned, and the bullets accumulate from all directions. But it may be just me, I'm not too good with WASD keys 😅I would have enjoyed being able to play using the arrow keys and space to shoot.
That's mighty impressive for a first game!