That cutscene at the beginning was super spicy. Love that lightning effect, I could really feel the oomph. Actually, I think it would be super cool if the lightning flash happened periodically as you played, with the volume decreased a little. The dark graphics are also super cool, and I really like that super intense music at the end. Really got my blood rushing.
One thing I would absolutely change: Either making double jumping the default, or remove the mid-air jump. It's super confusing not having a double jump, but having a mid-air jump, and I was stuck at a platform that I thought required pixel-perfect jumping until I realized I could jump in mid-air. The solid platforms should be a little brighter, they're a little hard to see with the dark background. I also didn't really feel the effects of the other robots other than the first one, it seems like the first robot gives you a major speed and jump boost and the other robots give you a minor one. I would have increased the default walking speed too, it does feel a little sluggish at the start.
Overall, very cool game, you definitely nailed the atmosphere. I had a lot of fun playing through it to the end.