You’ll spend a lot of time on your belly. Maneuvering takes place in fits and starts as you inch your way across the map to get the best position. By making the world as real as possible, and by making the AI ruthless, Bohemia has created a game of pure stealth, where the greatest moments are often terrifyingly tense. In one early sub-mission, we were ordered on a midnight raid into an enemy encampment to plant an explosive device near a group of tanks. The remarkable engine showed off a clear night sky, constellations twinkling, enemy campfires burning yellow and orange in the dark night.

It’s all about assimilating the data: the fires gave off enough glow to let us see the guards, and the guards themselves were constantly chattering to one another (albeit in co-ordinates: “Move to one zero one”). The darkness obviously gave cover, and approaching the camp it was necessary to lie in the long grass and watch the patrol route. But we got it wrong. On the approach we chose to run the tank about 20 meters ahead of us with no cover in-between. There was a campfire off to the right and a patrol suddenly passed between us and the tank. In any other game bullets would fly, but in ArmA we froze and then backed off slowly on our belly, somehow managing to keep hidden.

ArmA can be incredible, but the flip side is when it breaks it does so spectacularly. Another small mission asked us to booby-trap a bridge so that it would collapse, leaving the enemy forces with only one exit - through an ambush. We crept under the bridge, only to find its supports submerged. Given no explanation as to where exactly the charges should be placed, we slipped into the water. ArmA’s swimming is atrocious: we can only assume the water was fast-flowing, because it was like trying to breaststroke through a wall. Eventually we reached a strut, selected a charge from the menu (ArmA reuses Flashpoint’s clumsy collective menu system for selecting gear and actions), and... nothing. Now what?

Maybe we’re in an awkward position for bomb placement? Trying to move in the odd rushing water was a nightmare - we floundered around for a bit. Eventually we got a charge on the riverbed, although the opacity of the water made it difficult to tell. We had four more charges still to go, but the game said “Mission Accomplished” and didn’t allow us to plant any more, instead ordering us to the next waypoint to await the convoy. The order came in and... “Kaboom.” Except the single charge wasn’t enough to bring the bridge down, and the now alerted convoy backed off, causing the mission to fail.

Attention, Bohemia: it doesn’t matter if the tides are correctly modeled in your game if you can’t get the swimming or even the damn mission triggers right.