Probing the footage Relic's showing, one screen sticks out: a portrait of a marine with three attribute bars, a level count, and various other notes. But Dunn is quick to close that off to immediate interpretation. "The whole purpose of that is just to point out the idea that there are RPG elements," he says. "The design is not complete at this point, so which attributes are being upgraded and which pieces of wargear you're going to have aren't [set], but the idea is that through the canon, through the universe, the idea of the space marines and upgrading their armour and their weapons and the customisation of the gear for your character is really important within that universe, and that's something that's really important to this game as well." Whether you start off with a character and then mould him, or roll your own character, is unknown.
The nature of the combat is also a secret at this point, beyond what you can see for yourself. I ask about combo systems, special attacks and level design, among other things, but McFarlane and Dunn are guarded. "This is not like a Rainbow Six kind of squad or strategy thing," McFarlane will say. "It's high action. We call it 'RPG lite', you know - heavy on the action."
With four characters in the on-screen squad, Space Marine is obvious fodder for drop-in co-operative play, although Relic will only say that it's experimenting with multiplayer options - competitive and co-op. "We want this game to be playable with friends," says McFarlane. "It's a big focus."
One thing it's not doing though is a PC version, and Dunn gives the impression that in the same way THQ didn't feel Dawn of War was a good enough fit for console to warrant a port, it doesn't see Space Marine as a game fit for PC. "It's like, if God of War was on the PC, what kind of an experience would that be?" says Dunn. "And I think it's our idea that it wouldn't be the ideal experience. You could probably make it work, but it's not where the beat is and where the strength of the platform is, so instead of washing the game out so it's appropriate for multiple platforms, it's about building the game to the specific platforms that we want."
And for the moment, that's it. Our first glimpse of Space Marine ends as the orks set off a nuclear weapon on the horizon, hyping their troops in the foreground into a frenzy. The Ultramarines brace themselves against the onrushing wind and raise their weapons under the imperial standard, before diving back into battle and splashing ork blood into the waves of rolling dust. "What we really wanted to capture with this game is the violent, gritty nature of the Warhammer universe," says McFarlane. "This universe is constantly at war."
Although the vast majority of details are still to be revealed - and perhaps even still to be decided - the footage so far attests to that, spilling blood with abandon. And even with so many unknowns, Relic's devotion to the canon, and past work on Dawn of War, will write Space Marine onto a lot of most-wanted lists.
Warhammer 40,000: Space Marine is due out for PS3 and Xbox 360. There's no release date yet, but THQ told us "not this year".