When I looked at this, it really gave me goose bumps.. SO reminiscent of Neverwinter Nights 1. WOW! (Watch the video in HD, and just pause at some of the moments of in-game shots.. amazing art direction!)
And has co-op, a DM and a toolset?? Mayhaps an Escape from Undermountain 2?
Enjoy! (tray below lip to catch drool)