XCOM: Enemy Unknown guide - squad builds, ET tactics, base-building strategy and more

XCOM is back! And as you've probably realised from our XCOM review , it's brilliant, capturing everything we loved about the original game, but with lots of clever modern ideas thrown into the mix. The new game is different enough from the old one that even X-Com veterans could do with a few tips, never mind rookies. Thankfully I'm here to help. After spending many, many hours in the game, I've assembled this guide, collecting all the best tips I can offer to help you deal with the alien menace. What's more, you can also find Chris' video guide to surviving Ironman mode embedded above.

But, before we get started, here are some other XCOM tips you might be interested in:

How to recruit hero characters.

How to force the game to use 1080p cinematics.

The dev's own tips for taking down early-game ETs .

Building your Base

Restart after the tutorial – The XCOM tutorial is very handy for learning the basics of the game, but it's also very linear. Starting again after you've finished it will give you the freedom to plan your base how you like, and ensure you don't lose three men on the first mission.

Win the space race – If I could only give you one tip, it would be this. Build satellites. There are no second bases in Enemy Unknown, so it's vital that you launch satellites and buy interceptors in order to spot UFOs around the Earth. Secondly, each satellite you launch will provide extra resources and calm the nation it's launched over. Thirdly, when you complete the satellite coverage of a continent you'll get the same bonus you would if you put your base there. This is why it's pointless to set up in South America, since you'll only need two satellites to do the same job as a whole base.

Mine for steam – Thermal generators are way better than regular power generators, but they can only be built on steam vents. So the best way to produce power is to quickly mine down to the steam, build a thermal generator and then surround it with regular generators for the adjacency bonus.

Engineers are better than Scientists – Every item in Enemy Unknown requires a minimum number of engineers to build. Conversely, a single scientist can research everything in the game, extra ones just make it go faster. So if the game offers you a choice between engineers and scientists, go for the engineers. I've never built a single laboratory while playing this game, I've just never needed the speed boost. Workshops, on the other hand are very useful, granting you access to more items and refunding your resources.

Weapons versus armour – This one is a tough call. Armour is generally faster to research, as there are several different guns for each class, while one suit of armour fits all. If you've got veterans to protect, I recommend prioritising armour. If you're dealing with a squad of rookies (often the case if you're an iron man player) then I'd go for weapons instead. The upgraded rifles make noobs far more likely to actually kill something.

Train your officers – Building an officer training school gives you access to some powerful upgrades. You can improve experience gain, increase your squad size and make your soldiers more likely to survive. All essential if you're going to develop a veteran squad.

Combat Tips

Keep your ears open – As you move across the battlefield, you might notice sound waves coming from off screen. These are little clues as to where the aliens on the map are positioned, Firaxis' solution to all those old X-Com missions which ended with a half hour search for the final alien. As an extra bonus, the sound clip that plays at this point hints at what kind of alien you'll find. Stomping and Darth Vader breathing means Mutons, while skittering insectiod movement means Chyssalids.

Overwatch is key – Overwatch is XCOM's version of X-Com's reaction fire, and it's one of the most powerful weapons you have at your disposal in the field. Always have at least one or two men on overwatch to cover the rest of the squad before moving or ending your turn. The only reason not to have someone on overwatch is if you've already spotted the enemy and are busy filling him full of lasery death.

Exploit enemy movement – Whenever an enemy spots you, they are allowed one move action. Ranged units will panic and dash for cover, while melee units charge forwards. You can exploit this movement by putting your whole team on overwatch before moving the last man forward, this way if you provoke an enemy, they'll run right into your firing arcs and get horribly slaughtered.

Use stealth – That enemy movement I spoke about? It happens when they spot you, not when you spot them. This means that by using a Ghost Suit's invisibility, or the Sniper's Battle Scanner you can spot the aliens while they're still clustered together and they won't react until you've dropped a grenade right in the middle of them.

Make your own door – Back in the original X-Com, opening a door was suicide. Things aren't as bad these days, since you can now fire from cover at either side of the door. Still you can often surprise the enemy by simply blowing a hole in the wall with a grenade and making your own entrance.

Exploit explosions - Blowing up a UFO power source does some serious damage, but if you do it, you won't be able to salvage it at the end of the mission. However if you're using thermal power, you don't actually need that many, so you can happily use it to magnify take out the enemy. The same trick also works with cars, which is why you should never stand next to a burning one.

Next: Your squad and how to build them.