Hi, nice game!
Overall, I'd say that it's pretty decent especially since this is your first game (I think).
Gameplay - It could do with some improvements. Mainly giving the player slightly more room to jump and play around with the dash mechanic. Speaking of the dash mechanic, I really liked it. It's a neat idea and was executed well, so no criticism there.
Art - In terms of art, this game definitely succeeds. The BG art looks amazing and the players and enemies all look really good.
Music - The music bops but is a bit loud. Sure, you can just turn it down on your own machine, but a volume slider wouldn't hurt either.
Theme - The game definitely fits the theme well.