Starting from the menu I liked the background art with a palette of “greyish blue” giving out the space vibe. You could’ve added the hover effect on the buttons in Menu.
Even the in-game art style was <3 and the parallax effect was nice. But one couldn’t distinguish between foreground and background elements for eg. the pillar in the lobby when the game starts.
I found the walk animation was just two sprites changing rapidly. Also, one bug I noticed was that when you jumped to a higher platform you jump once more which shouldn’t happen. Adding some kind of distinct boundary to both the ends of the arena would be better.