I think you're off to a good start! I like the splash screen - reading the comments you didn't spend much time on the art, so thumbs up for producing something that cool.
I think there's room for improvement for the platformer mechanics - I think some acceleration / deceleration would give it a nicer feel. Check out that post by Zack Bell - he's my go-to reference for any game making programming! https://zackbellgames.com/2014...
Music is sweet too!