When they're not brain-washing us into hijacking ambulances or deep-frying our own household pets, videogames teach the virtues of inefficiency. Chalking up a double-figure killstreak in Call of Duty generally means deploying enough raw ordinance to powderise an asteroid. In Borderlands 2, meanwhile, you'll throw away randomly generated guns almost as often as you fire them.
Metro: Last Light is different. 4A's sublimely dirty post-apocalyptic shooter teaches that each and ever bullet matters - and not just because there's a short supply, but because the better grade of ammo doubles as currency to spend on fancier weapons at a handful of underground depots. Opt for spray-and-pray tactics early on, and you may find yourself facing down nastier foes like armour-plated neo-Nazis armed with a rusty horizontally-fed SMG. Secondary gadgets and gizmos are also subject to stringent limitations - those power-guzzling night-vision goggles won't help much if you've forgotten to crank your portable turbine, and without a decent supply of filters, strapping on a gasmask is about as safe as French-kissing a facehugger.
Metro isn't about killing, in short, though there's plenty of killing to be done. It's about survival. The irradiated ruins of Moscow have mellowed somewhat since the events of Metro 2033 - there are patches of blue in the pall, the ice has retreated in places and the vegetation has begun to grow back. It's a grubbily beautiful spectacle, easily matching the likes of Halo 4 and Crysis 3 in terms of both engine technology and art direction. But this has only made life harder for the city's embattled human population, as new and even more hideous species of post-nuclear monstrosity arrive to claim the streets.
Navigating a flooded square, you'll need to keep an eye peeled for the muck-spitting amphibians that lurk in pools of contaminated water. The world is noticeably more open than in Metro 2033, and somewhat unhelpfully, previous travellers have laced the wasteland with tripwires and other traps. Perhaps the greatest threat to progress, however, is the temptation to linger over the brilliantly realised small details - peeping beneath the seats of a butchered airliner, or studying a corpse for clues as to who or what killed him. Like Bioshock's Rapture or Dishonored's Dunwall, Metro's Moscow is littered with hidden side stories, pieced together amateur-detective-style as you pursue your main objectives.
The bulk of these tales are to be found underground, in one of the game's many ramshackle, gorgeously thought-out tube-station-cum-townships. Leading man Artyom will visit a fair few of these on his voyages, some populated by renegade factions, others by neutrals who will happily house, feed, rearm and entertain you between firefights (for a fee, of course). We've toured two of these cities so far - one friendly, one unfriendly, both equally fascinating. The first sees Artyom making his way through a neo-Nazi base with its own hydroponic garden, eavesdropping on guard conversations as he tiptoes along gangways.
It's possible to take a high action route here, assuming you're loaded down with ammunition, but most will want to play stealthily at least to begin with, shooting or unscrewing light bulbs to cloak your advance and using silent weapons like throwing knives to down suspicious goons. As in Metro 2033, Artyom's watch carries a light level indicator comparable to the gemstone from PC classic Thief, making it easy to keep tabs on how visible you are.