AB Rooms, shortened from Ambidex Rooms, are a core gameplay mechanic in Virtue's Last Reward. These six rooms in Warehouse A of Rhizome 9 serve as one of the main points of the game when making choices, the other being the Chromatic Doors. What endings occur and what happens to the other participants of the Nonary Game: Ambidex Edition mostly depends on what Sigma Klim chooses in the AB Room during an AB Game (Ambidex Game). Most choices made in an AB Game will lead to a Game Over. The rules of the AB Game can be found here.
Virtue's Last Reward
Sigma first appears in an AB Room when he wakes up from being drugged with Soporil, though at this point, it only serves as an Elevator, the first escape room and later second last in the game. It is later revealed that it actually serves as an AB Room and remains like that for the rest of the game, after Sigma and the others go through the first Chromatic Doors. Depending on the round of the AB Game, to enter the AB Rooms, the players would need key cards, which are found in escape rooms behind the Chromatic Doors. After an AB Room is opened, the players have 45 minutes to vote. If a player doesn't vote, they default to Ally. If a whole group of 3 doesn't vote, then they are penalized and killed by their bracelet.
Before Akane Kurashiki's body is discovered, Zero III moves the rightmost AB Room to the left side using a ceiling crane, in order to make anyone who discovers this not suspicious of Luna. The movement of the rooms also exposes Dio's Myrmidon knife. This occurs while the players are searching the Lounge, Infirmary, and Crew Quarters in the magenta and yellow routes. However, if Sigma chooses the cyan door and goes through the Crew Quarters, the room is never moved and Sigma and Phi never find Akane's body. This leaves her life in a similar position to the life of Schrödinger's Cat. In Phi END, Phi knocks Dio unconscious, which collapses the possibilities to one certainty and explains why Akane's body was never discovered on those routes: she is still alive.
- In the Security room, the monitor shows 7 AB Rooms instead of 6. This is likely an error.
- In Zero Time Dilemma, the AB Game is played between Carlos and Junpei in the Power Room. However, this time, if a player allies and their opponent betrays, the player loses 3 points instead of 2 and instantly dies, as do two other people in the shelter. The successful betrayer gains 6.