From Fallout's jazzy, shell-shocked America to the bleached dust of I Am Alive, the Xbox 360 has played host to a multitude of post-apocalyptic worlds, but this is the first time, to my knowledge, that it's given us a world that's in the process of getting better. Metro: Last Light occurs precisely one in-game year after Metro 2033, the grim yet startlingly rich exercise in tunnel-vision from 2010, and in that time, developer 4A's bedraggled depiction of Moscow has altered dramatically.
The radioactive snow has lifted, the ice has thawed, and the bone-grey colour palette is sodden with new life - yellow scrub and bacteria-slicked water, festering in the glare of a wan but strengthening sun. The transformation is driven as much by the need to show off new technology as plot considerations - in its understated way, Metro 2033 is one of Xbox 360's prettiest shooters, and the sequel should give Crysis 3 a run for its money.
Somewhat ironically, Moscow's recovering ecology has made life still more hazardous for the metro's ragged population of human survivors. Predatory fins arc from the waters of stagnant pools as our handler edges across a swampy square, eyes peeled for the red flags hung up by Rangers to denote safe crossing points. Gas masks are once again necessary if you want to move around above ground, and the environment's relative size and open-endedness leaves you considerably more at risk of surprise attack. A tense silence falls as returning lead Artyom scampers around, broken by the unearthly cries of unseen horrors. Noisy behaviour on the player's part can be suicide - it's definitely worth keeping a silenced revolver about your person, preferably with a scope attached.
Thanks to the retooled engine, the atmosphere has a texture so thick you can practically chew on it. Clouds of anomalous gas, streaks of drizzle across Artyom's mask (which must once again be topped up with new filters at intervals) and queasy patterns of sunlight are sources of fleeting fascination. Such is the layering effect, that it's occasionally easy to miss the tripwires linking dilapidated car hulks, and the small troves of precious ammo tucked into the crevices, generally accompanied by a corpse.
Our objective is to reach a nearby church, but in order to do that, we'll need to board a makeshift raft by way of a small diesel generator. This entails a couple of things: one, finding the fuel for the generator, and two, surviving the roused wrath of local wildlife once we hit the switch. The fuel tanks aren't too hard to find, though making away with the goods is another matter. As we're recovering the last of them from the cockpit of a downed airliner, something huge, green and reptilian seizes the craft's tail, shaking us around like a fly in a bottle. A few blasts from Artyom's deliciously complex six-shell shotgun put a stop to all this, but the worst is to follow.
The generator coughs and rumbles brokenly, drawing the attention of every living creature nearby like a magnet. While it hauls the raft across with agonising slowness, we're bombarded by screeching bat creatures, spat at by crustaceans and pummelled by the aforesaid huge reptilian something, whose armoured claws prove an efficient defence against bullets. Artyom's visor is soon covered with mud, but an outbreak of civil war among our attackers buys him a moment to wipe it clean.
The battle ends with surprising suddenness. Our man is left standing on a heap of perforated chitin, breath wheezing unpleasantly through the holes in his mask as he contemplates the remains of his ammunition. On the other side of the screen, by contrast, we're left wanting more. Metro: Last Light's world represents an important evolution of the one we saved from destruction in the original game, and providing the gunplay and level setups have also matured, this should be an unforgettable sequel.