Say what you like about Dawn of War and Company of Heroes - and if you're anything like us then what you will say is "they're awesome", in any case - but you can't deny that Relic knows and loves Warhammer 40,000.

Space Marine, a third-person hack-and-slash/shooter hybrid, is the latest example of that wonderful, contagious affection. Spend a few minutes with the multiplayer customisation suite - unlocked when you hit level 4 online - and you will probably find yourself rapt.

There are hundreds of possible combinations of pre-authored armour sets depending on the Space Marine chapter you favour, or you can come up with your own by choosing from dozens of colour and pattern variations. You can also customise your loadout with familiar weapons like the chainsword, melta gun and several different bolters, and choose from a range of perks, like Blast Off, where your jump pack engine exhaust causes damage on lift-off.

It all fits snugly together, allowing fans to recreate their perfect vision of a Space Marine for Relic's first third-person shooter in the 40k universe. For everyone else, it uses the tabletop game series' vast history as the basis for an interesting and intelligently assembled collection of loadouts, perks and classes.

Throughout the single-player campaign, too, you can feel the depth and proud history of the nearly 25-year-old 40k universe rumbling in the background. It's in the awed expressions of Imperial Guard as they first behold a Space Marine on their planet, and in the divisions within your Ultramarine squad about applications of the Codex Astartes, the sacred doctrine of the Space Marines.

The Orks all have wonderful Dick Van Dyke cockney accents. Spoice Maroine!

Indeed, whereas science-fiction shooter developers often tell us there are "many more stories to be told" in a universe we've spent two or three games plugging with bullets, thanks to Relic's fine detailing, Space Marine intuitively feels like just one story in a vast universe of many more, and we don't need to be told so.

Another handy thing is that, whereas most shooters ask us to believe that a random soldier can be a one-man-army and save mankind from certain doom, in Warhammer 40,000 the Space Marines are one-man-armies designed to save mankind from certain doom. So when you step into the chunky battle armour of Titus, an Ultramarine captain sent with a couple of squad-mates to the Forge World of Graia to defend its Warlord-class Titans - massive robots, basically - against a million-strong Ork invasion, it makes perfect sense. It's also a great setup for a game.

In this case, the game owes a lot to the first Gears of War. Framed from close over the shoulder, it follows you through strictly linear nests of trenches, corridors, tunnels and elevated walkways, frequently ballooning out into arenas where you are set upon by Orks and, later, the forces of Chaos, before narrowing again after they are all dispatched.

Being able to customise your Space Marines online is one of the best features.

Your broad mission is to secure the Titans, but along the way you meet a few people - a Lieutenant and an Imperial Inquisitor, most notably - and you chatter with them in person and over battle-comms as your objectives evolve.

Helping to fill out the backstory of Graia, which has been in the grip of invasion for just over a week, are a series of voice recordings you find lurking in corners and side rooms along the way. As is often the case with this sort of thing, some are interesting and others quite dull, but within 15 minutes of the start you won't be able to stop yourself looking around for them out of habit.

The big difference between Space Marine and Gears is that there's no cover system. Ranged weapons function much as you'd expect - iron sights with the left trigger, fire with right, and you can hold four at a time - but the majority of the time you will be going in hand-to-hand after firing off a few rounds to set things off.