Visually this is really nice. I love the glows you used on certain assets. Really fits with the old style PC monitor. The character and enemies looks great too. The exploding enemy characters was a nice touch too.
A couple of issues: I use a MacBook Pro as my main computer, and use the trackpad instead of a mouse so I found shooting awkward, it kind of needs a key mapped for shooting so that you can play with just the keyboard.
The other issue is that I got to a part of the level where I was at the edge of a ledge and I'd have to take a leap of faith because it's not clear on where I can safely jump to (screenshot attached). Platformers aren't games I would normally play, but I feel you should have an idea on where you can jump to, without taking that leap of faith, especially when dieing in this game sends you right back to the beginning.