As a Vim user I appeciate JKL as functional keys :)
Gameplay is simple to understand and play!
Sprites are cool and sfx are pleasing.
Some notes:
- don't really a fan when there are different pixel size styles in one project, it looks odd to me
- while not allowing player to shoot diagonally looks understandable in very low scale pixel art game it looks artificient in this one
Very nice entry! Good job!