Jake Solomon, the enthusiastic brains behind Firaxis' XCOM remake, knows some of you will be unhappy that the game has multiplayer. He saw the reaction to BioWare's announcement that Mass Effect 3 would have multiplayer - a first for the series - and is aware how opinion can, in the blink of an eye, sway from adoration to derision.

"You would expect people to be very excited," he tells me in the lobby of Firaxis' airy headquarters in Hunt Valley, Baltimore. "But sometimes people are like, it's a single-player game, why do they need to ruin it with multiplayer? Sometimes you'll hear that and you're kind of like, well..."

Well, indeed.

Multiplayer has been a part of the XCOM remake from the moment production began. And that was a long time ago - just over four years. From the very beginning, Solomon knew what it would be all about at its core: two squads made up of aliens and soldiers going at it using the XCOM turn-based strategy fans know and love in a traditional deathmatch set-up. Now the game is complete the multiplayer is fully fleshed out, but it's no more complex, really, than that original vision.

The first question that springs to mind is, why add multiplayer to the remake of the game so many loved because of its tense, tactical, unending single-player?

UFO2000 Gallery: XCOM multiplayer screenshots. That poor Sectoid. This content is hosted on an external platform, which will only display it if you accept targeting cookies. Please enable cookies to view. Manage cookie settings The units, how to use them, and how to beat them This four-legged alien is an expensive but powerful unit that can leap multiple stories and cover incredibly far distances in a single turn. It's especially good against human units because it can incubate an egg into their chest, turning them into a zombie that bursts, revealing a new Chrysalid. The Thin Man's strength comes from his value. He's a cheaper unit, but can leap on top of buildings and has high mobility, making him a great scout. But the Poison Spit ability is best. This area of effect attack makes enemies slower and their aim worse. Be careful, though. The Thin Man has few hit points. This melee beast has a huge number of hit points. He can run through walls and causes a lot of damage, so is useful against enemy soldiers and Sectoids. Every time you damage a Berserker he moves at the attacking unit, whether it's his turn or not. So you can, in a way, bait him. But watch out. His Bullrush ability means he can burst through walls to attack close up. XCOM's cheapest unit, the Sektoid's special ability is the Mind Merge. You can do this with any unit on the battlefield, soldier and alien, granting them extra hit points, extra critical hit change and improved aim. However, if the Sectoid dies while Mind Merged with a unit, that unit also dies. To combat a Sektoid, follow the Mind Merge trail, which is never hidden. It leads to the Sectoid, which is easy to kill. Down it, and you get two for the price of one. XCOM's most versatile units. Soldiers come in many flavours, and can be bolstered with extra inventory items, such as medkits and combat stims. XCOM's powerful Cyberdisc is very expensive, but it's worth it. Their mobility and power means they can devastate an enemy squad in just a few turns. And being up in the air grants a passive defensive bonus - not that the Cyberdisc needs it anyway - it has loads of hit points. You'll need snipers and powerful weapons to take this robot class unit down. "It's one of those fantasies," Solomon counters. "You played the original, it was always this fantasy to play as the aliens. Now, generally, the fantasy encompasses a game where you're aliens invading earth. But that has never appealed to me - I don't know that would actually be that fun to play. So this is one way to fulfil that fantasy. You can play as the Sectoid. You can play as all these different alien creatures. I don't know that from the very beginning we knew exactly what multiplayer was going to be, but it was something I absolutely wanted." There was something else, though, something more real than a fantasy, that convinced Solomon multiplayer was not only right, but good for XCOM. It was a mod for the original XCOM called UFO2000 - still played today - that Solomon adored. "It's this awesome experience," he says, fondly. "It was one of those passion projects by people. I'm sure there are people still playing it now. I knew it worked well. It's different. I always wanted to play as the aliens, so it was something we just always wanted."

Take your turn, but not your time XCOM's multiplayer is simple, really. You begin a match with a points pool from which you buy units you wish to send into the battlefield. All the units in the game are available from the off, from the Sectoid to the Thin Man, the Chrysalid to the Sniper soldier. Powerful units are expensive. Weaker units are cheap. There are variations of unit types, for example, The Sectoid can Mind Merge with a friendly unit for a turn, boosting its power, but the Sectoid Commander can mind merge with your entire squad. Of course, the Sectoid Commander is more expensive than the Sectoid. All the soldier types are available, but you can pay more for more powerful archetypes and items, such as medkits and combat stims. So you can, if you wish, pimp out a solider with Titan armour, a medkit and a snazzy plasma rifle, but you'll have spent half your budget on him in the process. On the battlefield, what strikes you first is how odd it is seeing soldiers and aliens in the same squad. Everything about the XCOM single-player tells us to hate the aliens, to fear them, to destroy them. When a Berserker bursts out of the fog of war it terrifies you. Now, I've got a Berserker watching my assault soldier's back. The Archangel soldier. AKA, jet packs! Thankfully, Firaxis has resisted the urge to tinker with the core XCOM gameplay for multiplayer, instead replicating it, more or less. A turn is limited to 115 seconds (this can be customised alongside the points pool). During this time you command each unit in your squad, moving, perhaps shooting, maybe using an ability too. Then, it's your opponent's turn. In the early game, you're focused on sending out units that can cover a lot of ground in one turn, such as the Chrysalid, the Drone or maybe the leaping Thin Man, to scout the battlefield. You'll want your snipers up on high ground where they can see as much of the map as possible. And you'll want your bullet sponges, your Berserkers and beefy soldiers, to begin their assault. During the first two turns you probably won't see your opponent's units. Then, you'll hear the shuffle of movement from the darkness, and out of the fog of war some nightmarish enemy type comes to tear up your carefully laid plan with its razor sharp teeth. Combat works as it should. In the XCOM remake, cover is essential. Leave a unit out in the open and they're dead during your opponent's turn. One of your soldiers dies from a sniper shot from within the mist and you wonder where the hell that came from. It's your turn. You have to think on your feet. There are 30 seconds left on the timer, which pulses red in the top right hand corner of the screen, and soon your opponent will bring his reserves out of the rear. It makes for a tense, fast-paced experience. Because of the time limit on your turn, you're forced to make decisions quickly. You can't sit there pondering your next move over a cup of Horlicks like you can in single-player. This is different. The time limit creeps up on you. The warning bell surprises you. During your opponent's turn you find yourself twiddling your thumbs, pondering your next move, contemplating which Pot Noodle to eat for dinner. During your turn there's never enough time. "In some ways it's straightforward, in some ways it's endlessly complex, in a good way," Solomon says. "All you have to do is kill the other enemy units. But what those units are is endlessly changing. The beauty of this is there is no perfect strategy. There is no strategy you could not defeat if you knew what you were going to face. "So if the player brings a bunch of hard-hitting Mutons, that's fine, those guys are incredibly tough. But one Sectoid Commander could mind control that entire squad. If someone brings a Sectoid Commander, that's fine, because you can just bring a Cyberdisc, which is a robot and is completely immune to psions. So there are endless combinations of units you can have facing off against each other."

Plan or die The trick, I found, was in creating a balanced squad, one agile enough to cope with whatever is thrown at it. In one match I was devastated by a fellow game journalist who brought three Cyberdiscs to the table. I brought three Berserkers, thinking the sheer brute force of the units would be enough to stomp out his effort. What I didn't consider, unfortunately, is that Berserkers cannot damage flying units. That match didn't end well. So I adjusted, ditching the Berserkers for more variety. I added a Thin Man (perhaps my favourite unit because of its useful poison spit ability), a sniper (for those pesky Cyberdisks) and gave my main soldier a rocket launcher. Oh, and I brought a Cyberdisk of my own. My final squad was: a tank soldier, a medic soldier (who I kept close to the tank), a sniper soldier, two Thin Men and a Cyberdisc, an expensive but essential unit for its manoeuvrability, power and death dealing from above. "You always want to keep your units mixed up," Solomon says. "It's a risk reward mechanic. You can go with all psionic units, or all tough units, but typically that means you're very vulnerable. All of these units have strengths and weaknesses. But everything is balanced in the points system." XCOM's multiplayer is an enjoyable experience, and I found it creeping under my skin, forcing me to think about strategy when I wasn't playing. That, in my experience, is a good sign, but with just five maps (perhaps more will be released after launch), no progression system and only online leaderboards to recognise player skill, I wonder if it will take off. But then I think, perhaps a mode like this is the only way to add multiplayer to XCOM. It can't have fancy social features and impact the single-player as Mass Effect 3 so controversially did because that would betray what XCOM is all about. "I would hope people would understand that all this does is add to the game," Solomon says. "Especially for people who really liked the original, it's really fun. It's a fairly straightforward mode. It's deathmatch. But it's deep and it adds a little more replay value to people who like the game. So I would expect general excitement with a couple of guys going, like, this is a single-player game! Why spoil it with this multiplayer!" One concern I suspect fans will have - and it's a valid one - is that the addition of multiplayer has diverted resources away from the single-player, that somehow the core XCOM experience is diminished because of it. That, and, well, that multiplayer is forced on developers by spread sheet-toting publishers who are desperate for fans not to trade-in the game. "The way it actually works industry wise is your publisher is always genuinely excited for multiplayer, because it adds replay value and longevity to the title so you get less resell," Solomon admits. "So if people go, we want to add multiplayer, then typically the publisher will go, okay, we will lay out for the extra features. "It was never explicit. With us, it was always like, we want to do multiplayer, and the publisher was very excited to hear that because multiplayer adds a lot of value both from the development side and the fact people will play the game for longer. Although our games typically have a lot of replay anyway, it adds even more value for games with short single-player campaigns and limited replayability. But yeah, it was never explicit with us. It didn't pull anything away from the single-player."