This differs from the previous routes as follows:
- A matrix is not a railway because all the stations are linked to each other; you don't need to go A-B-C-D, you can go A-D-B-C or any other combination if you start from A - which is entirely up to you. Starting somewhere is useful, even in media res.
- A matrix is not a museum because there are no guided tours. People can still wander around like in a museum but there is nothing steering you. You can walk, swim, fly or tunnel wherever you like. Any sense of sequence arises from game play or narrative.
- Increased versimilitude - You know how easy/difficult it can be to get a Japanese samurai into a European medieval setting? So you can say yes/no with confidence or even maybe if you feel so inclined. Everything hangs together, you know your neighbours.
- Players get to determine their own damn route - this is the holy grail if you're ready for delays in achieving consensus or bad decisions based on whimsy, player boredom or trust games (if I go to a dragon, will you sic it on me?) for you.
- Wherever you go, you're prepared. So your players want to go see the mountain witch to get the river-dragon's curse removed? No problem. You know what's on the way, where they have to go and how much trauma they will experience.
- Game balance and discretion - if your dragon lives in that particular area and the 1st-level party want to start a fight then it's going to be short-lived. Signposting is helpful but to some gung-ho types, this is a red flag situation and they need to be educated.
- Short-cuts for linear plots - will occur. Linear plots can be entirely circumvented or surgically truncated in a matrix setting. Derailed plots usually end up in chaos, sometimes lovely, sometimes a mess. Your mileage and improvisational skills may vary.
- There is more work involved. Not just the preparation of each border but also possible directions the player can travel and the overall intention of the game. You can get by with sketchy areas in a railway or museum plot but white space in matrix plots is bad.