It sounds like a poor man's Team Fortress 2 in third person.
So Orcs Must Die with full-assed base building rather than just the traps? And 4 player co-op? I can dig it.
Still pre-alpha though? Wasn't this announced 2 years ago? I figured they'd be further along
I for a moment thought it was by the same guys as Torchlight, but I am wrong.
Could be interesting.