Popping everyone into teams of two gives each player a buddy, sidekick or rival (delete as applicable) and allows for mobile respawning, a la Battlefield: Bad Company, which adds plenty of additional layers of tactical consideration into both attacking and defending teams - it's often quite a good idea to drop out of combat and hide in a nice quiet spot for a few seconds for your partner to spawn on you.

The difference between Spartans and Elites is more than cosmetic. Elites are much faster, spawn with their ubiquitous energy weapons and can select loadouts that give them the ability to do that annoying weaving dodge thing from Halo's old single-player campaigns. Spartans, on the other hand, get UNSC weaponry and shiny visors.

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Selectable loadouts exist across all modes, and are a bit like Call of Duty's Custom Classes only without the option to modify them outside of custom games. They determine your starting weapons and your additional armour abilities, such as being able to sprint (self-explanatory) or use a jetpack, which is useful to get a height advantage but a bit too slow to be used in combat. Other armour abilities include Active Camo, which returns from previous games and a temporarily impenetrable shield that also doubles as a cheeky EMP blast with the Armour Lock ability.

The final new mode is Generator Defence, a 3v3 mode on Overlook that pits Spartans against Elites, having the latter trying to destroy three generators within a time limit. Those handy with their arithmetic will have already spotted the mode is half the size of Invasion, so matches are played on smaller maps and are tighter, more intimate affairs with an even greater focus on solid teamwork.

As it is also entirely obligatory for a modern to have some kind of persistent unlock system, Reach uses XP to signify rank and as an in-game currency, allowing players to save up and eventually go shopping for new bits of armour. There are also long and short-term challenges for players, which I presume will offer up some kind of tiny image emblem, and possibly an achievement, when obtained.

Weaponry has been modified, with the ever-famous Battle Rifle being retired (or just not existing yet, as Reach slots into the Halo saga as a prequel), though the new Designated Marksman Rifle does its best to park in the vacant space. There's also a fancy Needler Rifle, which combines the Covenant's purple exploding shards with the ability to be fired across long distances, as well as a tweaked Plasma Rifle and a new UNSC Grenade Launcher that can cook its shots. And the Magnum - it's not a Halo game without the ridiculously powerful Magnum, after all.

It's all tied together with the promise of a vastly improved (although Halo 3's is still one of the most accomplished on Live three years after launch) matchmaking system, notably sporting the option to join friends' games automatically when a slot opens. There's also the option to define your social settings, giving you the option to choose between categories such as 'rowdy' and 'polite' - although it's unclear how are going to filter out the inevitable masses of players who nip into 'polite' channels and start cussing like sailors.

So far, so Halo. But familiarity, and accessibility, has always been one of its strongest suits. It's always been gaming's comfortable pair of shoes; the pair that always feels supremely comfortable and oddly empowering, despite the fact your Mum tells you they're tatty and you should throw them out. There's a lot to like, and a few things that could be a little better, but throws just enough novelty and refinement into Bungie's familiar mix to coax a warm, fuzzy feeling of something both reassuringly old and excitingly new.

The Halo: Reach beta is available through the 'Extras' menu on Halo 3: ODST starting May 3.

By Martin Gaston