Oof! The cutscene at the beginning had me shooked, I love how cinematic It looked, plus the thunders and lightning effects! You perfectly built an intriging and misterious narrative with that simple cut scene!
As for the gameplay, I agree with some of the comments here about the speed of the player, however, I totally understand the point of it, I wouldn't change the default speed, what I would do instead is place the first boost robot near the beggining, so the user can easily understand what the game is about!
For the art style, the background is nice! Maybe add a little more 'depth' effect, it can be solved making it a bit blurry for example! or making it darker so that it seems that it is behind the player and not in the same 'layer'.
The color palette is gorgeous! Purple, blue and dark red make the great mix for a misterious/nostalgic scene, well done!
I can see a lot of talent here, so congrats for such a cool project :D