So hard to rate a game of a jam.. I think the experience is overall pretty good but I'll speak as if it was a finished game :
The first impression is really good because graphics are clear and colorful! Too bad there's no music to boost this impression, I would have rated it 4 stars without hesitation then!
The 1st (and only "real") problem I encountered is "I don't know when I die". Then I understood that the character gradually disappears, but it's still hard to see when we die. Maybe adding a sort of lifebar would be clearer! The other issues are not so problematic: hard to figure out the collision zone of spikes, and sound is saturated when collecting coins in a row.
Otherwise the game is pretty challenging (in a good way!), controls respond well and you put a real effort on dialogs!
In short, it doesn't lack very much to become a great game! Really just musics in my opinion. Well done!