Clear Sky is another iteration on the way to what GSC Game World PR director Oleg Yavorsky calls its ‘dream game’: one set in an AI-driven and realism-focused freeform world. Its predecessor, Shadow Of Chernobyl, was a bag of progressive ideas that jostled against each other, leading to an uneasy tension between freedom and script. With 18 months of development time on top of the first game and the benefits of DirectX 10, Clear Sky is an outstanding second go.

Most immediate are the improvements to the graphics engine – Yavorsky takes us into the game’s opening area, a ramshackle settlement. The models and textures are more detailed than in the original and it’s shot through with God rays, and this with just a DX9 build of the game (it will also support DX8).

A later demo of the DX10 effects that GSC will be applying to the game demonstrates volumetric smoke and steam that has physical properties (swirled into eddies by moving objects and flowing around them) and ‘dynamically wetting surfaces’ – environments that wet in rain, with puddles forming, but that stay dry under cover. It all adds to Stalker’s special air of authentically dilapidated naturalism, all the better to make The Zone appear real. “We want to stick to photorealistic environments to make it look authentic,” Yavorsky says.

Chief among the more intrinsic improvements to the game, hoping to bolster the effects of players’ actions in the world, is further development of the ALife system that governs the actions of animals and NPCs in the world. Clear Sky has a new focus on the struggle for power between its four factions: each has its own base, storyline and unique characters; moving up in the ranks will result in more involving missions, and helping your faction rise in stature will provide players with bigger, better equipped squads and a greater number of friendly outposts scattered over the world, many of which are won by players as they travel through it.

An extremely capable squad will often accompany the player character on missions, able to take on outposts occupied by enemy factions and wandering creatures with little management. Yavorsky begins an expedition into Marsh, one of the six new areas (for a total of 12), and his Squadmates immediately take crouched stances. Finding an outpost, Yavorsky pauses to explain their capabilities – how they can autonomously accomplish missions and tasks – and while he’s talking they happily mop up all resistance by themselves. While there’s a danger of such autonomy taking away some of the player’s pivotal agency in the world, it gives the sense that it’s living around you.

But while GSC has worked hard to make Clear Sky’s play flow more naturally in a naturalistic world, it contains various anachronisms that other open-world games have long since dropped. The Zone is still not a seamless, streamed world. “We’ll have to stick with loading locations – the problem is that you need to choose between going for high detailing and being seamless,” claims Yavorsky. “We have these complex geometries and details, so if we went for seamless environments we would have to sacrifice that.” It’s still interface-heavy, with a HUD including mini-map, stance indicator, ammo gauge and so on all clustered at the edges of the screen, and missions are doled out in text boxes with dialogue choices.

Such throwbacks can’t help but remind us that Far Cry 2 is following closely on Clear Sky’s heels, a game with many of the same goals as Stalker’s but with a better integrated interface, leading to a concern that perhaps it’s already too late to build the game that Stalker should have been.