This is a mix of two types of games I love, very clever idea ! For sure moving the hero is a nightmare and take too much time, but the concept can be easily changed.
a) Once there is no more enemies in the room only tiles for movement fall down, this should already make the game much better.
b) Once there is no more enemies in the room, maybe you just have to click on items to collect them, having to move to get all the items is a real nightmare.
For the rest, this game is a great idea, I would love to see an improved version of this great concept, with maybe a better IA for the enemies too. I hope you will go on and improve this game.