My new game is out, go buy it.

[Firecrest]

You earn two stars if Heroes take treasure from your treasure room, but you manage to kill them before they leave with it. You get one star for having at least one treasure remaining in your dungeon (anywhere) and three stars if all treasure remains in your treasure room at the end of the level.

Ah. I'm pretty sure this was not explained as part of the tutorial on stars.

Which is another thing. Needs a way to go back and review tutorial data.