Gentlemen! I had loads of fun with this game! It's nicely done. I'm missing a few things, like end-game screen and durations of weapon pick-ups, and also sometimes my enemies just got stuck behind the spawn barrels and if they were outside the screen I was confused on why I don't progress.
But overall, the game has awesome feel and I really feel good playing it. The best things are the variations with the dark level for example and the sound design, that's awesome! (Good job J4kub0k)