Shogun 2: Total War

"With a Japanese castle, they look around, find a big mountain or hill with a clear view of the landscape, and chop the top off it. Then they build low walls on top of that - but what we'd regard as the castle walls are really just the sides of a mountain."

As a result, siege weapons become pointless. Instead, those inside the castle can be starved out (boring, if effective) - or, if very confident, they may actually open the castle gates and allow their attackers to enter, hoping to turn each courtyard inside into a death trap for any unwary enough to try their luck.

"The Japanese idea is to open the gates and say, come on in if you're hard enough," says Simpson. "You end up with courtyard-by-courtyard gameplay with different routes through, different traps to fall into - and for the defenders, lots of different options to choose from, too."

The game isn't due out until 2011, and although the team fidgets excitedly when I ask about multiplayer, they refuse to be drawn on their plans other than to say that it's "something very big and very cool, which we can't talk about yet because we need to make sure that it works before we go and blab about it." Wise words - take note, fellow developers.

Returning my attention to the screen, I note that a new strategy is emerging - perhaps a slightly more desperate one, in light of the corpses of our brave pikemen which now litter the muddy hillside.

Across their bodies, the enemy's swordsmen charge, an unwavering line of thousands of samurai, swords aloft and glittering in the moonlight. Hastily organised rows of our own samurai brace themselves in a matching line, as more flaming arrows begin to arc through the sky towards us.

With a clash, the armies meet across a front almost a kilometre long. Untold dozens fall in the first moment, as striking distance is reached and blades fall - then utter confusion reigns, as the front lines fracture and samurai scrap with each other in the pouring rain.

Martial prowess on full display, the swordsmen dance around each other, flashing blades striking like steel cobras at arm's length. What seems like a disorganised melee from a distance resolves, closer to the eye, into a thousand individual duels, each seeming exquisitely choreographed in its deadliness.

It's not going well for us, though, as our foes' flaming arrows continue to do their work. Finally, the demo player reveals his trump card - an elite cavalry unit, which has circled around behind the enemy archers using the cover of a misty valley and a densely wooded hill.

Howling, they descend on the lines of archers, speed and height advantage leaving the bowmen defenceless. Stripped of their support, the enemy lines waver; moments later, our cavalry rush them from behind, slaughtering their back lines before plunging into the fray to claim more honour, more glory.