At the moment of writing this I have only played about an hour of Hammerwatch, so feel free to disregard my "review" if that doesn't seem like enough to get a fair taste.
I have always disliked the control-style Hammerwatch uses, but it also implements a few nifty commands that actually makes it work rather well. It does takes a bit of getting used to - unless you're familiar with and/or comfortable with this type of controls - but you should quickly get a hang of it.
From what I've gathered this is a game about navigating a labyrinthine dungeon of numerous levels, finding secrets and solving simple puzzles, gathering money-loot and buying skill/ability upgrades, last but not least, it's all about killing hordes of beasts and other foul beings.
A keyboard-based (or controller, I think, haven't tested) hack&slash for singleplayer or co-op.
If you like the abovementioned concepts and don't mind getting lost now and again, then I'd recommend you Hammerwatch.
(If my opinion should change I'll come back and edit this - unless I forget to)