This was lots of fun, and very true to the theme: Hades, the original underworld!
There are lots of ways to "solve" each room, but that doesn't detract from the puzzle-rpg cross-over feel. Along those lines, perhaps there could be an extended-play mode with randomly generated rooms; I suspect you can find the right balance between "can just make a bee-line to the stairs" and "no way to walk into the room without taking damage".
My only complaint was that it was a bit unintuitive how to "aim" things like charge and boulders. I didn't realize at first that charge actually needs an open space between Heracles and the first monster, nor was it immediately clear that boulders were targeted by clicking one of the four tiles cardinally adjacent to Heracles. (I at first tried to click the monster I intended to hit instead.) A visual cue like always highlighting tiles a selected action can affect could help with this. Also, I found myself clicking an already selected action in attempt to deselect it; that might make sense as an alternative to right-clicking.