(CNN) — Escape rooms are having a moment. They're the No. 1 local activity for a number of cities around the world on TripAdvisor, and they've been featured on reality shows such as "The Real Housewives of Beverly Hills." But don't worry if you've never heard of them; this is your explainer.

Escape rooms are simply mental puzzles played out in the real world's 3-D glory.

Each word-, number- or logic-based challenge in a given escape room, once solved, opens a literal or figurative drawer or door to reveal another important clue. Each solve gets players closer to beating the overall game. In some cities, you escape zombies, while in others, you break out of jail.

If this reminds you of a video game, it's because some say the genesis of the rooms were Japanese gamers who created IRL (in real life) versions of their favorite virtual spaces.

Others argue that they originated with the (super) smart set; MIT's Mystery Hunt has been around since the early 1980s. The MIT games involve more than just puzzle smarts, and include genuine scientific skills like wet-lab testing, DNA examination and thorough scientific knowledge. But they do have a lot in common with escape rooms.

Those who excel at crossword puzzles and number games tend to love escape rooms, since it brings their skills to bear as part of solving a larger puzzle. But unlike doing an acrostic or Sudoku, or even a labyrinth or maze, escape rooms aren't a solo solve-it experience.

"They're a super-fun thing to with a group of people; they're not something to do on your own," says Cat Bohannon, a Seattle-based science writer who has tried several rooms. "Preferably you have at least three to four people, though some are set up to be a couples thing. But it's better for a double-date situation."

Many escape rooms are organized so that you can bring a group of people and have the room to yourselves, while others might match you up with random strangers to solve the puzzle.

Since time in the escape room ranges from an hour to 90 minutes, strangers can actually be an interesting dynamic.

"You never really know what someone's secret nerd-dom is. Maybe they're really good with word problems or finding patterns or brute force solutions when other people are looking for complex answers," says Bohannon.

Finding out what everyone's good at is part of the fun, whether you know them or not.

That said, escape rooms are never a guaranteed win. Especially if you've never done one before, your group can easily fail the challenge in the allotted time given. Your mission to save the world from aliens or knock down the Berlin Wall could flop, and it's these "real" stakes that may be what keeps people coming back for more.

Strike Exitus in Sydney, Australia

Jacqui Angus, the brand manager for Funlab, the company behind eight escape rooms throughout Australia, says her best advice is to newbie puzzlers is: "Bring your cleverest mates."

Strike's rooms run the gamut when it comes to themes which include "a space station, a casino heist situation, a haunted house experience and a computer meltdown drama," says Angus.

She says that choosing which motif suits the group is part of the fun, especially for new players. Each room is ranked by difficulty and "anything could be a clue to move you forward," she says.

Sydney-based nurse Giulia Moretti visited the "Forensic" game which featured a set of rooms. "The first one was a police station setting, the second was a bunch of old evidence including bones and a skull, and the third was the scene of the most recent crime. It was super creepy," says Moretti, who adds that she and her friends didn't solve that room but still loved the game.

Strike Exitus , 22 The Promenade, Sydney NSW 2000, +61 1300 787 453

BreakOut Escape Game in Singapore

Palo Alto-based Lauren Joyce discovered escape rooms during her studies abroad in Singapore.

A friend organized the night in the "Magician's Revenge" at BreakOut. Even though none of the people in the group had participated in an escape room before, the ambitious grad students chose one of the tougher challenges. (BreakOut has six rooms: Three are easier and three are more complex.)

"Here we were, a group of pretty competitive people, many whose jobs require solving complex problems—yet we couldn't crack the codes. We had nothing on the regular escape room fans/groupies who know more about the types of patterns and clues to look out for," says Joyce. Despite the fact that her group didn't crack the case, she said it was a fun, dynamic night out and she wanted to try another room elsewhere to practice "being a cryptologist for the night."

BreakOut , 31 Kreta Ayer Road, Singapore 088998, +65 6226 2688

Make a Break in Berlin

When Sydneysider Giulia Moretti visited Berlin with her boyfriend Richard Neo, they heard about an escape room that featured a famous local landmark.

"The mission was to get to the other side of the Berlin Wall (they actually had a fake wall put up in the room) and to send a radio message to tear the wall down," says Moretti.

There were other escape rooms to visit in Berlin, but they specifically though visiting one with a local theme would make a great site-specific memory of their trip. "There's always a sense of accomplishment when you crack some sort of code or get through a door," says Moretti, which keeps her going back for more escape room fun when she travels.

Make a Break , Müggelstraße 8, 10247 Berlin, +49 30 31171383

Ninja Escape in Seattle

Seattle's Ninja Escape is, according to John Harlacher, game designer and co-owner of the company, a "gang" of six games, all with one storyline. "It's a connected universe," says Harlacher, who got his start creating haunted houses and theater sets in New York City.

University of Washington grad Kayur Patel, who has completed about a dozen different escape rooms, says he loves the challenging puzzling aspects of these games. But he also really appreciates the great production design that go into some of them, citing Ninja Escape as an example.

Harlacher says he's inspired by getting the feel of a 1980s video game into real life. "We have visual effects as well as sound effects—if you open something, there's a happy sound, or if you do something wrong, there's a bad sound."

Patel has gone to escape rooms for a bachelor party and with cousins during a family reunion.

"It's a good non-food/non-drinking/non-museum activity that we can do. It does work as a bonding event, and it's also time-bounded. It's only an hour, and after an hour you're done," says Patel.

Ninja Escape , 3800 Aurora Ave N #270, Seattle, 98103, +1 (206) 257-4907

OMEscape in San Jose, California

OMEscape is a franchise location of a Chinese escape game company, but the local owners made changes to the story lines to fit the local market.

Their most popular games include the all-ages-friendly Kingdom of Cats in which the kitties are in charge and the humans are the outsiders who have to compete with the smarty-cats to get back home.

Pandemic Zero features multiple rooms, including sewer tunnels and science labs. And Sorcerer's Sanctum, one of the toughest games, features advanced technology.

With five different rooms all rated by difficulty level, the company really tries to cater to all different types of groups who might want to try solving a room. "The goal is to have fun with friends, not necessarily to 'win'," Sarah Zhang, the manager of OMEscape says.

She also reminds us of the most important aspect of escape-room success: "Don't give up!"