Wall Trading

Independent of game mode it is possible for players to trade walls among each other. This is an extremely strategic option that players can exercise at any moment during game play.

Wall trading is not free though. For each game variant the cost of a wall is determined at game start. This cost is used to calculate the final score of each player when the game is finished.

Wall trading is a two phase process:

Phase 1

One player makes an offer to either buy or sell a wall. Each transaction can only be exactly one wall and when the player makes a sell offer it must have that wall available. The offering will create an in-game message so other players know there is an offer on the table. However, the offering player can choose to make the offering private by creating a direct message (DM) to a specific opponent (only meaningful in a 4 player game).

Phase 2

Players that can read the offering message can make a trade that is compatible with the offer. A sell offer is transacted by a buy trade and a buy offer is transacted by a sell trade. If a trade is made one wall is moved from the available walls of the seller to the available walls of the buyer. On top of that the wall cost will be deducted from the final score of the buying player and added to the final score of the selling player.

note

Multiple offers can be done by different players in the same game.
Also, a player can have an offer outstanding while trading with another player.
A player cannot have multiple offers outstanding.

The strategic aspect is that although the selling of a wall would help an opponent, one can increase their own score doing it and decrease the opponents score at the same time. Each player in the (possible) transaction must make up their mind if this is good for them or not.

note

Offers can go unanswered.
Offers can be withdrawn.

Trading cost

Each wall trade has a point cost that affects both players' final scores. The buyer loses points equal to the cost; the seller gains them.

The base cost depends on board size and player count. Smaller boards and fewer players make walls more decisive, so the cost is higher.

Base cost per wall

Board	2 players	4 players
5×5	8	6
7×7	7	5
9×9	6	5
11×11	6	4
13×13	5	4
15×15	5	3
17×17	4	2

Wall mode multipliers

If wall modes are enabled, the cost increases to reflect the extra strategic value of walls when information is hidden.

Mode	Multiplier
Normal	1.0×
Masked only	1.3×
Invisible only	1.5×
Masked + Invisible	1.8×

The final cost is base_cost × multiplier, truncated to an integer. You do not have to remember this or calculate it yourself. The wall cost is part of the full board display.