An effective, properly executed atmosphere can turn a fun, yet forgettable game into a memorable adventure.

That’s exactly what 4A Games accomplished when building the alluring and intriguing world of “Metro.”

In “Metro 2033” and its sequel, “Metro: Last Light,” you play as a Russian who, like the rest of Moscow’s residents, lives in the decaying subway system beneath the city. The world above was nuked to oblivion, and radiation pockets and swarms of mutants make it dangerous to venture to the ruined surface for too long.

As a result, the Russians have made the metro system their home. Living in the gloomy darkness, people have congregated in different parts of the subway tunnels, forming small communities where they use coveted military-grade ammunition as currency to barter for food and other essentials.

You spend most of your time in both games fighting mutants and other hostiles in secluded parts of the metro, but you occasionally get to roam through these shabby hamlets.

Families live in cramped rooms poorly constructed from rotten plywood and old sheet metal. Certain areas act as taverns and brothels where depressed residents numb their pain with alcohol and sex. People eat rats and other filth while others try to distract themselves with guitar playing and shadow puppetry. Glances at these hovels demonstrate how terrible life underground would be.

A running theme of the “Metro” games is claustrophobia. Even the more open areas these colonies provide still feel cramped and crowded. The discomfort is suffocating, adding layers of tension to an already unsettling game.

Suffocation becomes a literal threat when you roam through irradiated metro tunnels. Communities are separated by miles of metro tracks, and if you don’t have a cart to quickly and safely get you from one settlement to another, you have to walk (often alone), and you’ll encounter hazards along the way.

Your guns are important. They let you fight off mutants, Nazis and communists that have invaded abandoned areas. You won’t get far without spending your precious bullets on the various enemies who want you dead.

But just as important as your guns is your equipment. Your lighter can burn away spider webs as thick and heavy as blankets. Your flashlight is all that separates you from utter darkness, and you have to occasionally pump a hand-operated device to keep it working.

Your gas mask has a limited number of filters you have to swap out periodically to avoid suffocating. The mask can become cracked and smeared with blood and other fluids as you’re fighting, requiring you to wipe it off or even switch it out when you come upon a dead explorer.

These systems exist to create a sense of realism and desperation. The games still would be fun if your gas mask filter never had to be swapped out and your flashlight’s battery never died, but having to manage your equipment gives the games more depth and adds to the ominous tone.

Occasionally you have to make your way to the ruined surface. Outside area are the games’ most hostile; a gas mask is essential, and bloodthirsty mutants roam free. But with sunlight, unhindered skies and open spaces, these sections rob “Metro” of what makes the series’ underground levels so delightfully unsettling. Thankfully, they never last too long.

The shooting is fine, and the story is OK. But in both “Metro” games, it’s the creepy, unsettling atmosphere that makes me excited to turn out the lights and get lost in the decrepit ruins of Moscow’s subway tunnels.

Video game columnist Jake Magee has been with GazetteXtra since 2014. His opinion is not necessarily that of Gazette management. Let him know what you think by emailing, leaving a comment below, or following @jakemmagee on Twitter.