Call it the new nerdcore: RPGs are big business. Dungeon Siege 3 is entering the cave-complex that Diablo, Dragon Age and Torchlight have called their own. What can it bring to the ornately carved game-table? A hefty weight of physical violence. Drop-in, drop-out cooperative dungeon crawling. Gorgeous new technology. And intricate business manoeuvring.

The private demo I saw was little more than a proof of concept. A dungeon, two heroes (a warrior and a wizard) and a steady stream of ugly baddies. The bads got knocked about like toys – the warrior slamming his shield into entire groups. It's simple bash bash bash entertainment. The wizard fights by the warrior's side – one is controlled with a gamepad, the other with a mouse and keyboard. Their abilities are complementary, the wizard slowing or freezing bigger enemies in place while the warrior carves a safe path through them.

The technology is impressive. The dungeon they're fighting through is miles deep. You can see it spiralling down into the depths. Each little goblin that gets knocked off the ledge can be seen pinwheeling into the river below. This isn't an off-the-shelf tech solution like the Unreal engine: this is developer Obsidian finally flexing their technical muscles.

And that's the other weird surprise. Hold tight, this is complicated financial stuff. The original Dungeon Siege was developed and created by Gas Powered Games, led by Chris Taylor. The Dungeon Siege games and intellectual property were sold to Square Enix. The same Square Enix that created the Final Fantasy games, and then merged with UK publisher Eidos (themselves the owners of Deus Ex and Tomb Raider). Square Enix, in turn, have contracted out development of Dungeon Siege 3 to Obsidian, the team behind Knights of the Old Republic 2, Neverwinter Nights 2, and in their former iteration, Planescape: Torment and Fallout.

Why is that surprising? Because Obsidian are all about story and lore and detailed moral consequences. The Dungeon Siege games were mostly about turning orcs into piles of guts, and overloading your pet donkey with loot.

Which is why when lead designer Nathan Chapman talked about “paying respect to the Dungeon Siege lore,” I had to stifle a giggle. The Dungeon Siege lore is what director Uwe Boll used to make a four hour epic. It's not exactly Shakespeare. Expect slick cutscenes with Mass Effect style dialogue – they're not going to hang about making you read pages of quest text. Unless they're daft.

Being grumbly at this stage seems churlish. Obsidian have great tech, smart dynamics, and an ambition to create a fleshed out RPG. Success isn't assured – but they're already on the right track.