Some general feedback, in no particular order:
1. Add some sounds, especially to revolver (I like to add placeholder sounds as early as possible)
2. Timer, maybe with "time to beat" would be a nice feature, and would make me take risks. For example on "day-night" I just sort of stop during the "night", but if there was a timer ticking away I'd be willing to take a leap of faith just to beat it
3. I like how levels progress. First ones are pretty basic, then the revolver is a nice addition, and the final one makes good use of color, and fog.
4. Restarting levels could be faster. Check out how its done in 'hotline miami' or 'celeste'- restarting after failure is keypress away.
5. This is personal opinion, but for me fake platforms feel like the game's cheating. Like- if I fail on the last level (again, the best one) it's because I mistimed a jump, wasn't fast or precise enough with my shots. You know- my skill wasn't up to the challenge. Fake platforms have nothing to do with skill- I thought the platform is there, but, oops, it's a fake one!
6. Last level again! Man- I just loved the moment I figured out the best way to beat the purple- red platforms at the start was jumping over two at once, and then try to shoot the red one!
Over all- this is one of the simpler submissions, but I like it! Keep up the good work!