My first time around I somehow managed to give an extra key to something, leaving me with -1 keys. It's also not clear which chests accept 2 lots of treasure and which don't. It was only through trial and error that I figured that out in the first place, I thought I was missing a room, or there was a hidden passage or something.
If you expanded on the idea this game could have legs.
Like having to place traps, or avoiding setting off traps meant for the hero, or both. Make it a puzzle to figure out the correct order to enable the traps and allow you to get to the exit without setting them off.
There's a whole bunch of dungeon related tropes you could play off of with this.