i loved this game! it's pretty addictive and i can totally see myself play hours! it's really complete and has a lot of upgrades which is great for a jam game, very well done! the idea is very cool and the art is also nice. it seemed a little hard to apprehend at first, because the mage killed all my skeletons and i didn't see i had spikes but after that all went smoothly!
here are the only things i would like to see if ever you want to make a full game out of it: a way to keep the speed value (i was at speed x2 during all the runs but i had to select that speed again every time) and a way to have the camera centered on the hero so i can have a full playthrough of their run without having to dezoom a lot