Its pretty playable. I like the atmosphere, cavern ambient with water drops feels nice! Пещера)
However, the game feels rather unfinished in scope.
No character or level designs (or is it intended to play as sketch? A Fancy-Pants, flash style?)
If you really decided to take part of MarathonJam, you can make your own version of Spelanky, but fast-paced and more concentrated.
Imo, its fine to take some tropes from other games but by taking risks and experimenting, you can create your own unique experience.
I see potential in the core gameplay loop!
So good luck with MarathonJam, this might a be great game in the future.