As is often the case at large press events, our recent brush with Halo Wars took place in a room where the number of journalists eclipsed the number of test consoles by a ratio of about three to one. In this situation, you simply have to hang around and watch someone else play until they're done, at which point you hopefully get to sit down and try the game yourself.

So, on a wet and windy evening last week we found ourselves at the Peter Harrison Planetarium in Greenwich. After a quick presentation from Ensemble studios, we joined the scramble to grab a controller. As predicted, we failed to reach a free console in time - so instead we perched behind a friendly-looking guy in a smart shirt. Did he mind if we watched? "Not at all," he replied. "But you're going to watch me being crap."

He wasn't kidding. Whoever the nice man was, we doubt he'd played many RTS games before. After working through the tutorials and the basic first level, he started out on the second mission in Halo Wars' main campaign - a stage which serves as the proper introduction to developing a base and building your army. The scenario is that you've just recaptured a UNSC outpost that was previously overrun by the Covenant; your objective is to stop the alien cult from destroying a relic they've found nearby. You have to produce a small force and then send it to the north of the map, moving past a Covenant base in the process.

Unfortunately our poor comrade found this quite challenging. For a start, he didn't seem to grasp how Halo Wars' construction system works. Rather than simply building an HQ and then dumping other structures nearby, as is typically the case in RTS titles, bases in this game are located on specific sites. Each USNC outpost has a limited number of slots which can house the buildings you need: barracks and vehicle depots let you create troops, reactors give you access to better technology, and supply pads give you a slow-yet-steady stream of resources. You can eventually use upgrades to increase the number of slots you have to work with, but the core principle remains the same: either you build more supply pads to increase your cash flow so you can pump out troops quickly, or you use the space to strengthen your forces.

But as we say, the guy we were watching didn't understand this. He built one of each structure and then left the rest of his base empty. Then he'd build a couple of marine units and a warthog, which he'd then send up the map to awaiting Covenant - where they would promptly die. At this point he'd return to base and build the same combination of units, who would also be sent to their untimely deaths. He actually managed to make some progress with each attack - thanks largely to the efforts of Sergeant Forge, a hero unit in a Warthog - but it was taking him ages. It was like watching an ant trying to eat a wedding cake.

Why do we tell you all this? Well, because it serves to demonstrate the game's design. Our subject may have made a mountain out of a molehill, but he got there in the end. With a bit of experimentation - and a few nudges from a nearby Ensemble dev - he got the hang of things. It took him just shy of an hour to complete the level, but he did it - and by the close of play, he knew how it all worked. He was queuing up reinforcements while his main force pushed ahead, he was using his units' secondary abilities, and he was kicking asses and taking names.

The point, of course, is that Ensemble really has succeeded in making a highly intuitive control system. A lot of the people who will buy this game will be Halo fans who haven't played many RTS games. They're likely to be better gamers than our man in Greenwich, but they'll still appreciate a setup which lets them control their armies swiftly and coherently. And on the flipside, we can equally recommend the system for those of you who are familiar with the genre. We did finally get a go, and when we did we completed the level in under 20 minutes. It's simply a great control setup: you can grab individuals units with a tap of the A button, or hold it down to summon a larger selection circle. Double tapping on a trooper or vehicle highlights every unit of that kind, while RB gives you everything on-screen. Whether it's jumping back to your base, triggering a special attack or setting a way point, nothing feels 'far away'. Everything is within easy reach, and the result is that you're twice as likely to use these tools.

We're hoping the game manages to capture the excitement of the FPS series

Ensemble tell us that there are 15 missions to the central campaign. That's a reasonable total, but each stage will also have optional objectives to complete which improve your score and win you a shinier medal on the end-of-level stats page. On the stages we played, these bonus goals included the destruction of a Covenant gas refinery and the elimination of 20 Jackal snipers; both tasks required a bit of exploration away from the main thread of the map, and we reckon there's scope for more complex requirements later in the game when the action gets tougher and more complex. Here's hoping.

Once you're done with the campaign, there's always the skirmish and multiplayer modes. It's here and only here that you'll get to play as the Covenant. It's a bit of a shame that there's no main game for the religious nutters, but playable-in-skirmish is clearly better than not-playable-at-all. We didn't get much time to try the cultists out last week, but from what we've seen they offer a decent alternative style to the USNC. The bread-and-butter grunt teams are usually weaker than their marine counterpoints, but a Covenant player can turn things to their advantage through the clever use of their leader - a special one-off hero unit who empowers everyone near him. A Covenant force will only have one of these at any given time, but they come in a variety of flavours and have different special abilities. There's also a very cool feature that allows you to march troops into a particular structure at your base and then warp them directly to the leader's position. This opens the door for some crafty tactics, but naturally there's a risk in sending your most powerful unit deep into enemy territory, since you'll be at a big disadvantage if they get cut down. As we say, we've only had a brief encounter with the Covenant as a playable force, but from what we've seen so far we'd say they're a bit reminiscent of the Egyptians in Age of Mythology; veterans of that game may do well here.

While we're very sad about the closure of Ensemble Studios, we're mildly comforted by the fact that its final game is looking like a winner. The in-game graphics are crisp, colourful and beautifully animated, combining the charm of the developer's previous titles with the iconic designs and sounds of Bungie's landmark series. The cut scenes look damn impressive too, although we still don't know an awful lot about the plot. What we do know is that Halo Wars is set on the planet Harvest, some 20 years prior to the events of the original Halo. After a gruelling five-year battle, the USNC has regained some control from the Covenant, but the planet is still a hellish warzone. We're imagining that the discovery of the aforementioned relic will play a key role in the story, but it'll be interesting to see how the writers handle a story that takes place so long before the exploits of Master Chief and co. The strength of the this narrative will play a large part in determining how Halo Wars is received by the series' massive fanbase, but personally we're just happy with the way the core gameplay appears to have turned out. Lately there have been several attempts to create the definitive console RTS, but the contest is far from won. If Ensemble can pull it off with its final game, it would be a gratifying swansong indeed.

Halo Wars will be released exclusively on Xbox 360 in February next year.