Linear rooms lead you through the puzzles/locks in a specific order. In nonlinear rooms, there are multiple puzzles/locks that you can work on in an unspecified order. Obviously most rooms are neither entirely linear or entirely nonlinear, but most rooms can be placed in one of those two categories by looking at the general flow of the room.
I conducted a survey of over 250 escape room enthusiasts, and less than 22% of them prefer linear rooms to nonlinear rooms. Granted, almost all of them prefer a combination of the two, but based on their comments, it's pretty obvious that their opinion is developed by frustration with bottlenecks and lack of creativity of many linear rooms.
Number of Players
Because I usually play with only one or two other people, I choose to play a lot of linear rooms, but because I think teamwork is one of the most valuable and fun aspects of escape rooms, the escape room industry must prioritize the development of strong nonlinear rooms. When you play an escape room with only two or three people, teamwork is easy, but very small rooms have a hard time tackling nonlinear rooms. Linear rooms often create bottlenecks that cause everyone to work together. That makes rooms easier for small groups but frustrating for large groups. When small teams do attempt nonlinear rooms, they end up separated most of the game working individually on puzzles with very little teamwork or time to help each other.
One benefit of linear rooms is that the player gets to participate in all or almost all puzzle solves in the room. Unless you are soloing a room (and that is very rare), you will inevitably miss some of the puzzles in a nonlinear room, and as a puzzle lover, that's not ideal for me. For this reason, escape rooms must do a better job of recommending rooms for group sizes not only based on the size of the room, but also based on whether it is linear or nonlinear.
Defining Terms
Because website don't use the terms linear and nonlinear to describe rooms, I usually call to book rooms, but even then it is difficult to find out if a room is linear or nonlinear. I recently asked an escape room owner if one of her rooms was linear. She said, "No, it's not linear. You'll have to go back and forth between a few areas." Her response confused me, and I discovered that she thought "linear" means that once you leave an area of a room, you don't return to it. I played the room, and although we did have to go back and forth between areas a few times, it was a very linear room. When we entered the room, it was obvious where we should start, and we followed a very clear chain of puzzles through most of the room. That was fine for us that day because it was only my wife and I playing. This tells me that the solution isn't only to clearly label rooms as linear or nonlinear, but also to clearly define our terms.
Linearity is not about the order of the puzzles or the space that the puzzles are in, but about the number of puzzles available to a team at any given time. In nonlinear rooms, you may even solve a puzzle to retrieve a key that opens a lock that is not yet available to you. You'll have to retain the key until the lock is available. In nonlinear rooms, one of the biggest challenges is to connect puzzles to the locks they open. That's why I believe game designers should provide clues (especially in nonlinear rooms) that help players connect puzzles to locks.
Clue Everything
Because trial and error is not a fun form of puzzle solving, every task, puzzle, and lock in every room should have a clue pointing to it, but this is especially true in nonlinear rooms. In linear rooms, there's usually not many options available to a team so not cluing might be understandable in a few cases, but in nonlinear rooms, disrupting the feeling of immersion by requiring trial and error, or excessive searching, takes away from the fun of a room. Even if the task is to search for something, the players should know they should search for something. This is usually done best with lighting, arrows, colors, symbols, or word clues. If there are two letter locks available to the team, when a team discovers a word key, there should be at least a small clue/code with the key that points them to the correct letter lock.
With that said, there should only be one clue for each lock/key connection. If there are two clues that connect a puzzle to a lock, a team might discover both clues and think they are being told to interact with the same lock twice. Don’t point a team to a lock twice unless you expect them to open it twice, and that almost never happens.
Over the years I've come across a few rooms that use the same code/key to open multiple locks. In my opinion, it revealed a major lack of creativity or lack of budget. When a lock is opened, it should be assumed that it can be ignored for the rest of the room, and it is ideal that locks on doors remain unlocked after they are unlocked. If you use a keypad to open a door, the door should have a device that holds the door open so that the players don't have to repeatedly unlock a previously unlocked lock.
Creativity
Because linear rooms add suspense to a room, many good suspenseful rooms are linear. Austin Reed, an escape room enthusiast, said, "A linear progression keeps 'fear of the unknown' levels high." If the room is more of an immersive experience than a puzzle room, and if the room has a thrilling genre, a linear path might not be a bad thing. Haunted houses are linear, and people love them. If puzzle solving is not the focus of the room, providing enough puzzles so that everyone can be involved may not be necessary.
Because I am a puzzle lover, many of my favorite rooms are somewhat linear, but they have a few different puzzle paths. That can be achieved in a few different ways: including multiple storylines, using puzzles that have multiple stages, or requiring multiple puzzle solves for one lock.
For this reason, nonlinear rooms usually require more creativity, but linear rooms fit more logically into most storylines. I appreciate storylines that are so creative that they can include the complexity of multiple storylines without making the story too complex. I've seen this done with a story that requires players to escape a room while collecting evidence, to steal items while distracting the security guards, to launch a spaceship while disarming a bomb, to sneak onto a pirate ship while searching for a treasure, etc. Multiple storylines allow a team to spread out and even work at different speeds through the room's storylines.
Good nonlinear rooms often have complex puzzles with multiple stages. You might complete the first step in the first area then complete the second step of the puzzle in the next area. In this case, it will feel like there are more puzzles than locks because the puzzles have multiple stages, and I love rooms with multiple complex puzzles.
More often than not, there should not be many more locks in a room than there are puzzles. It is fun to quickly unlock multiple locks. This happens when you unlock a drawer that has a key in it that unlocks a box that has a key in it that unlocks a door, but I've played too many rooms that have a chain of locks to unlock that are not connected to puzzles at all. That reveals a lack of creativity. I played a room a few weeks ago that was really just a room full of locks with a few puzzles mixed in. The last four locks simply concealed a key that opened another lock. It was fun to open all the locks, but as a puzzle solver, I felted gypped. My five year old son could complete a room full of keys and locks. It may be fun to open a lot of doors and boxes, but many disconnected puzzles or locks in a room simply make most storylines unrealistic.
Bottlenecks
Large groups should not play in rooms that are very linear because rooms are more fun when everyone has a part to play. Most players like nonlinear rooms because they eliminate bottlenecks for teams of three or more. If there is ever only one puzzle available in a room with more than three or four players, some players will inevitably become disinterested and even distract the players who are solving puzzles.
Bottlenecks are most often avoided not by adding a storyline but by requiring teams to solve multiple puzzles to open one lock. That happens when you have to solve one puzzle to get the first digit in a code, another puzzle to get the second digit, another puzzle to get the third, and so on. This is a way to add creative puzzles to a room without having to complicate the story line. One of my all time favorite rooms required us to solve multiple puzzles to retrieve items. We didn't now what the items were for until the final puzzles required us to assemble the items to create a robot that opened a safe. We kept thinking we should be looking for numbers to open the safe, but we were actually building a robot that new the code to the safe. It was brilliantly creative.
Alpha Players
One of the benefits of nonlinear rooms is that they reduce problems caused by alpha players. Alpha players are players who attempt to effectively do a room alone in the presence of other people. They usually order the other players around while making themselves a bottleneck. Nonlinear rooms force teams to spread out. When the team recognizes the alpha is not capable of solving every puzzle alone, the team will begin to spread out and ignore the alpha.
