Cool game ! I definitely could this be expanded and have more levels and mechanics.
- It really lacks even a bit of sound, maybe you could have found some assets online and then wrote credits where you credit them ? or use tools like jsfxr (online page to generat 8 bit SFX), it would probably be really cool with more sound
- I think ther shoud be something enticing the player to be precise; I realized that you can just aim to the side of the screen , and go up and down very fast with your mouse, and it gets the job done without thinking too much, maybe if the laser had some travel time or something, or maybe if ennemies had a weak spot ? Or make it so that ennemies don't take damage as long as you haven't stayed 1 second focused on them ? Because you can try it, fire the laser everywhere quickly on one side and it will clean the stage ^^