Really amazing job. One really incredible thing done well in this game is choice. On my first playthrough, I didn't take any risks and ended up a small weakling on level 3! On my third, I did as many enemy rooms as possible and I felt incredibly strong even at level 1! This is an awesome mechanic.
For the sake of feedback, I point to things like having an "enemy death" noise, and having a just-hit-blinking with invincibility for a second or two after.. or else you can lose 5 hearts in a single go just like that! And for a roguelike that ain't cool.
Really awesome job. Hope you end up in the top 20!