I appreciate you made this in really limited time, but there is literally no game element in here. You just stay still, keep down the mouse button and there's literally no way you can die.
Probably better to implement the suggestions below, some other ideas:
- Limit the lifetime of a bullet
- Make the enemies enter the screen on random spots
- As soon as you did that, make the bullets a bit less random, or make it so that you can at least predict with a certain chance where your bullet will go, otherwise I think it might be too annoying