This might actually be one of my favourite games on this site in general now lol
Absolutely love how well paced and tightly designed this game was. Everything from enemy variety to general level design was amazing. Also love how some levels were basically just joke levels so to speak like the train level. The art was also beautiful and very expressive for how minimalistic it was
That said I think the spikes need some tweaking. I think the collision box could be a little thinner. Also I think the colour of it's sprite could be a little different. They tended to blend into the environment to the point that I couldn't see them in general some times. This was prevalent moreso in the first few levels where the animation effects for the rain falling on the ground basically looked the same as the spikes. I also think the level where you need to shoot at that alarm could've had a different coloured and maybe slightly larger arrow to indicate it or something, because I didn't notice it until after a few deaths.
Also, this might be more of an issue of personal preference, but I think there should be a delay before you're allowed to press the menu buttons at the end of a level, mostly because I accidentally restarted almost every level after I completed it. I also feel that maybe the drones should have only 1 hp, but maybe that's just a skill issue.
Overall though, amazing game here with tons of personality for how small it is. Really great stuff