TopHero is a small game -- just 8 levels, and likely less than an hour to complete them all. But it's an unusual one, and well conceived for what it is.
In each level, there is some sequence of hexes through which a hero must move to reach the level exit. You are a dungeonkeeper, and you have a variety of traps and monsters you can place in empty hexes; there may also be some hexes that assist the hero by healing him or providing new armor.
Your goal is to reduce his health to zero before he reaches the exit -- or rather, to arrange your assets in such a way that there is no chance that he can reach the exit before dying. Each of the assets has a set of abilities, viewable by mousing over it -- e.g., the Sphinx gives the hero a choice between losing 3 health or becoming confused (and other assets may affect the hero if confused). There's no randomness here; the hero will choose whichever option allows him to survive, if any.
Once you have arrayed your assets, you 'test' them, and the hero slowly progresses through the level, with text showing what happens at each hex, and either you've 'solved' the level or have failed and may retry it.
It's quite a nice little game -- and given that my main complaint is that there isn't more of it, that's hardly a negative.