Gameplay
Like its predecessor Metro 2033, Metro: Last Light is played from the perspective of Artyom, the player-character. The story takes place in post-apocalyptic Moscow, mostly inside the metro system, but occasionally missions bring the player above ground. Combat alternates between the player fighting mutants and hostile humans. Areas are larger in Last Light compared to 2033, and the game encourages exploration by having multiple routes. The game offers more freedom to players, allowing them to utilize different tactics to combat enemies. It features destructible environments, in which certain objects, such as pillars, collapse after being shot. Numerous diary entries, written by Artyom, providing additional insight regarding the game's story, are scattered throughout environments for players to collect.
As a first-person shooter, Metro: Last Light features a variety of firearms, some fictional and some based on real weapons, which the player uses in combat. The game's protagonist, Artyom, also has the ability to kill an enemy directly with his melee weapon. Artyom has three weapons slots. Players can put any weapon into these slots without restriction. Players have access to four different secondary weapons, including throwing knives, incendiary grenades, and hand grenades. Mutants do not possess weapons and tend to physically attack the player in swarms, while humans fight with the same firearms available to the player. The player can knock out or kill most human enemies instead of shooting them, using stealth to avoid detection. As enemies are inefficient in spotting the player character in darkness, players can turn off oil lamps and light bulbs to gain an advantage over their opponents.
In the post-apocalyptic environment, ammunition is a rare and essential commodity. Pre-apocalypse, military-grade ammunition is used as currency. Players can avoid consuming all the valuable currency by using lower quality bullets made within the Metros. Due to the scarcity of ammunition, a crucial aspect of gameplay is scavenging. The player can loot corpses and the environment for spare ammunition, as well as weapons and other items. The military-grade ammunition can be used to purchase other ammunition, weapons, and items within most of the Metro stations. Weapon attachments, such as scopes and silencers, which improve weapon efficiency, can be purchased with these bullets.
The game's locations reflect the dark atmosphere of real metro tunnels, with added survival horror elements. Paranormal phenomena, such as shadow figures, hallucinations, and unexplained noises are present, and, for the most part, the player has to rely on their lighter and rechargeable flashlight to navigate the darkness. Locations' layout is often intricate, and the game lacks any form of map or objective marker, leaving the player to try finding their objectives with only a compass. The surface is more lethal than the metro system. Featuring a day-night cycle, and a dynamic weather system, these sections are severely irradiated and a gas mask must be worn at all times because of the toxic air. The player must collect air filters for the gas mask. These last several minutes each, and are automatically replaced provided the player has more in reserve. Players also need to wipe off the dirt and blood splatter that collects on the gas mask. There is no head up display indicator to tell how long the player has until the gas mask's filters begin to fail — rather, a timer on the character's wristwatch shows how long until the current filter expires. The watch also serves to indicate to a player if they have been exposed to enemy attention. With every weapon, the bullets are (partly) visible, informing the player that their weapon is about to run out of ammunition and they have to reload. Instead of head up display the game makes use of audio and visual cues to present information to players.
There are certain subtle moral choices in the game that provide karma. Good karma can be acquired by good actions, such as rescuing people from enemy characters, listening to conversations between NPCs, or sparing enemy soldiers. Bad karma can be acquired from evil actions, such as killing people randomly or stealing things. Karma affects the ending that the player experiences.
Plot
Metro: Last Light takes place in 2034, one year after the events of Metro 2033, following the ending of the original novel in which Artyom's missile strike against the Dark Ones — mysterious beings that seemingly threatened the survivors of a nuclear war living in the Moscow Metro — occurred. The Rangers, a neutral peacekeeping force that operates throughout the system, have since occupied the D6 military facility Artyom visited during the first game. This is a huge, and not fully explored pre-war bunker, and Artyom, now a Ranger himself, remains unsure whether killing the Dark Ones was the correct decision. Rumors of D6's discovery and its great riches have spread around the Metro; rival factions, such as the Soviet Red Line and Nazi Fourth Reich, hope to seize the bunker and its contents.
Khan, a wandering mystic, informs Artyom and the Rangers that a single Dark One survived the missile strike. Khan believes that it is the key to humanity's future, and wants to communicate with it; Colonel Miller, the Ranger's leader, wants to eliminate it as a potential threat. Miller sends Artyom to the surface, accompanied by Miller's daughter Anna, the Rangers' best sniper, to kill the Dark One.
Artyom finds the Dark One, a child, but is captured by soldiers of the Fourth Reich. Pavel Morozov, a captured Red Line soldier, and Artyom escape through the Metro tunnels and across the devastated surface. When they reach the Red Line, however, Pavel is revealed to be a high-ranking officer; he detains Artyom to learn more about the Rangers and the Dark One. Artyom escapes and races Pavel's forces to locate the Dark One and Anna, who has been kidnapped by Lesnitsky, an ex-Ranger and Red Line spy. En route, he finds a contingent of Red Line forces massacring the inhabitants of a station, supposedly to contain a mysterious epidemic. It was the Red Line that introduced the virus to the station – weaponized Ebola acquired from the D6 vault by Lesnitsky. Artyom finds Anna and frees her but they are exposed to the virus and are quarantined after the rescue. Afraid that she will die, Anna seduces Artyom.
After they test negative for the virus, Artyom again encounters Khan. They locate the young Dark One, and in a series of hallucinatory flashbacks, Artyom recalls that he was saved by a Dark One as a child; he was psychically linked to the Dark Ones, intended to form a bridge between their species and his. Artyom vows to make amends by protecting the little Dark One, and the two travel to Polis, the Metro's central area, where a peace conference regarding D6 between the Rangers, Red Line, the Reich, and neutral Hansa is taking place. Artyom defeats Lesnitsky and Pavel during the trip. Along the way, the little Dark One senses that there is a group of hibernating Dark Ones in D6. After arriving at Polis, the little Dark One uses his telepathic abilities to make the Red Line leader, Chairman Moskvin, publicly confess that the peace conference is a diversion to enable General Korbut to seize D6. Artyom and the rest of the Rangers rush to the bunker to make a final stand against Korbut's army but are incapacitated by an armored train ramming into their station. Red Line soldiers surround and prepare to execute Artyom and Miller.
The karma the player has acquired determines the ending. In the "bad" ending, Artyom destroys D6 to prevent Korbut from using the facility to wipe out the remnants of the other factions and possibly humanity, resulting in the deaths of himself, the surviving Rangers, and the Red Line forces. Later, Anna is shown telling their son of Artyom's bravery. In the "good" ending, later revealed as the canonical ending, Artyom prepares to destroy the bunker but is stopped by the little Dark One, who, along with the awakened Dark Ones, defeats Korbut's army. Artyom calls the little Dark One humanity's "last light of hope". In both endings, the young Dark One leaves with the surviving Dark Ones to find safety, while promising that they will come back in the future to help rebuild the world.
