While the CRT shader is neat, and can fit a retro theme, it would be nice if there was an option to turn it off. It felt a bit overdone.
The game could use with some instructions/controls being added to the game page. When I started I was not sure what to press to continue. I tried clicking the mouse around, then space and enter, before starting to press random other keys before finding that Z advanced the dialog. Pressing escape gave me a black screen, and I had to refresh the page to continue trying things.
I don't feel like I really understood the game mechanics. It talked about building up speed, but I found the best way to win was to stay close and just keep hitting the enemy. When I moved away and tried to build up speed, I couldn't seem to do it well enough and when hitting the enemy generally took more damage than they did. When close and hitting them often and fast, I was easily able to beat them.
It fits the theme pretty well. Once I found the controls it was simple enough to play. A bit of a tutorial level to teach the techniques and practice would be nice. It wasn't really my thing, but it felt like a decent base for those who like this style.