Pacman, but turnbased and with items/abilities was the original inspiration. I'm very happy that shinned through.
Your suggestions aren't too far from what I have planned. I'm currently working on tile sets for castle walls and forests. The idea is to progress through a series of levels with themes. (start in forest, then caves, then dungeon, etc) I just didn't have time to get it done in time for the game jam deadline.
I've been very torn on the idea of a boss. Its something I've thought of, but never made up my mind on. 1) I'm not really sure how that would work in this format. The player has very limited attacks, and the enemies just try to ram you. 2) the idea was to have the floors be endless, with the risk keep multiplying. (I have code for scaling difficulty that goes to Risk Factor 150).
Something I've considered, instead of a boss fight, was a Treasure Room: A capstone level with a TON of treasure chests in a central chamber, but absolutely swarming with enemies.