This article was originally published in PC Gamer UK issue 252 .

There is a dead body in the cockpit of my MH-9. In my haste to get into the cerulean sky above Arma 3's Stratis island I accidentally spawned a chopper with a pilot in it and he wasn't budging. I could have hopped back into the editor and fixed it, but I was keen to see the island. And I had a rifle.

So I shot the pilot and then the co-pilot to save him from having to explain to the pilot's widow, and hopped in. The co-pilot remained, dead, slumped in his seat, his hand still gripping the joystick, as I flew around the rugged little Greek island cooing at the sights.

"the newest version of the world's most famous milsim is still ridiculous, and I love it for that."

My girlfriend, who started to watch after hearing me giggle at the hunched dead figure, found this distasteful. To placate her, I popped back into the editor and switched a few things around. Like Craig the Magnificent, I produced a bunny. I began hopping around the island, showing her how the game allowed me to control the body of a rabbit. Arma 3, the newest version of the world's most famous milsim, is still ridiculous and I love it for that.

This alpha is the public's first opportunity to advance into Bohemia's long-held territory. Pre-order and you get access to it right away. It's not the full thing by a long shot, having just twelve varieties of gun and eight types of vehicle, on a test island that's a mere 20km2 chunk of rolling hills with a few settlements dotted around. The full game will have a 270km2 island.

You do get 'showcases' of the scripting and scenarios the game is capable of, however, and while they're pretty small scale, they give a taste of what the infantry, ground vehicle, underwater and air combat will be like. More importantly, the alpha comes with the full editor and will support modding. People have already made zombie mods and co-op missions. There's a lot of game here for £20, and it's only going to get bigger.

I didn't realise how important the ridiculous part of the game was to me until I was in Thumper's body. I had feared that Bohemia's drive to make Arma 3 accessible to everyone might smooth its edges out too much. But no, it remains true to the original template. It won't stop you doing what you want, either in terms of mods or you own playstyle, for the sake of military-realism aesthetics.

"People have already made zombie mods and co-op missions."

When I played the first showcase, a gnarly little fight for a village that tore up my squad on more than one playthrough, that willingness to let events go where they wanted, even if the player was pushing in an odd direction, was much in evidence.

The infantry showcase reveals Arma as a well-matured game series: the changes are numerous, but built on top of an already impressive skeleton. Animation and movement are a lot smoother, and there's a new stance-adjust system to exploit, which is important in this lumpy, rocky world. Each stance – prone, crouch, and standing – has high and low variants that give you extra height or better hiding potential.

When the first stage of the fight kicked off, with my team at the bottom of a valley protecting a crippled soldier as enemies closed in, it took a few restarts to get back into the Arma way of things. Hiding and firing helped. I was cowering really, as the bullets pinged all around me, and I dropped into cover behind a cluster of rocks. My AI squad leader was marking targets for me to fire at, and even managed to sound human while doing it. My new ability to peek made the cover a lot more useful, enabling me to aim up and over without exposing myself too much. I didn't hit anything, but my shots forced the enemy into a position where the AI squad could take them out.

"I watched my squad push up against buildings, hunker down beside walls, and imagined the enemy doing the same."

Stage two: we're sent up and over the hill into a village. The world is full of lovely little spaces like this, and this one, a cluster of buildings hugging the coast, would have been welcoming if the enemy wasn't already in it. Another small squad, but this time they had buildings to shelter behind as we approached from our slightly hilly vantage point. This battle was tougher: the squad AI is surprisingly capable, and every building has an interior, so everywhere is a potential trap. I watched my squad push up against buildings, hunker down beside walls, and imagined the enemy doing the same. We all came together in one of those awkward 'everyone turns the corner at the same time' moments, but my squad was quicker off the mark and the enemy were soon all dead. We had a few minute's grace to look around, but before I had time to start renaming roads after my pets, mortars started to pummel us and I was volunteered to stop them.

I had to hunt the mortar spotters down. I wish I could tell you the next sequence was a tense battle through the undergrowth, but the truth was the AI spotted them up in a cluster of rocks north of our position. I'd already skipped (hammer 'V' as you run) up the hill to look at a little church, so I was parallel with them when the information came in. All I had to do was crouch-run along the lip of the hill then push in when I was close. I sighted them and swapped to the underslung grenade launcher.

Boom! My revenge for their shelling of Craigtown. Then I was told to run, as the enemy were about to shell this place, too. Spoilsports! I celebrated my victory by roly-polying (go prone then hit the lean key) down a hill and met my squad the bottom, who were fleeing to the trees.