What worked:
I really like the firing modes of the gun. It is really fun to propel yourself around recklessly. It's wacky and goofy in a good way, reminding me a lot of Newgrounds type games (Battleblock Theater, No Time To Explain, Castle Crashers).
What didn't:
It's a bit tedious having to check every dark corner for enemies. It really slows down what feels like a fast-paced game.
I would have liked to see interaction between the two firing modes. As it stands, each one activates by itself, but I kept wanting to light boost, dark swing, dark swing, then light boost up a ledge when I fell a bit short. This suggestion is entirely up to you of course since it drastically changes the game. I think this could be implemented by having the firing modes set to separate timers so you can't spam either one, but can activate them one after the other. Also on this note, I'd have loved if the light blast gave you more of a midair boost, but I understand why it doesn't since it seems heavily momentum based.
Checkpoints would be appreciated. The main area is short enough that it's fine, but it doesn't feel good having to restart hell the bouns level.
Bugs:
Didn't see any
Great job!