Quite fun! Definitely needs a few mini-bosses or stuff, difficulty curve seems too linear.
OR change it so that there's only 15 or 20 levels, the game is a little too long for the few new mechanics introduced.
Would be also nice to buy a card/inventory slot for 20-30 gold also.
I tend to have 30+ gold by the ends of runs just awkwardly sitting there, lol.