Double Go is like normal go, but with each player placing two stones for each move. These stones need be in no particular type of connection. Captures are only made after both stones are placed.
An alternative to komi in Double Go is for:
- The very first move to consist of placing only one stone. This is also an alternative to komi in normal Go.
- The first N double moves to need to be in a particular type of connection.
Go with multiple stones placed per move gives rise to /Limbo positions.
Note that captures occur at the end of each turn, so it is not possible to flip a (single stone) ko and fill the space in the same move.
(single stone) kos are resolved by using one stone to flip the ko and one stone to play a ko threat. /Limbo positions will end a ko, as both stones must be played to save a limbo group.
Seki positions can occur between two groups with unequal numbers of eyes below 3
The bent four leaves only one eye in double go, so neither player wants to capture.
- First Line Territory: 1 to 9.
- Second Line Territory: 9 to 19.
- Third Line Territory: 19 to 29.
- Fourth Line Territory: 29 to 39.
- Fifth Line Territory: 39 to 49.
- Sixth Line Territory: 49 to 59.
- Seventh Line Territory: 59 to 69.
- Eighth Line Territory: 69 to 79.
- Ninth Line Territory: 79 to 89.
The First Line Territory are too small, and the game is about influence. The Second Line Territory is not really a valid territory line, as the second line is difficult. This is more about tactics with equal territory and influence. The higher ups are more toward territory development first but by using tenuki moves to get sente in most subareas.
Most standard Board Sizes are at the top of each "Line Territory".
9x9 for first. This is for capture go and probably Fuseki (game) tactics.
19x19 for second. This is for tactics and probably Fuseki (game) strategy.
29x29 for third. This is for strategy. Any size this or beyond is probably for Fuseki (game) operations.
39x39 for fourth and beyond. These are for operations.
Because 19x19 is large enough for strategy to occur, 12x12-13x13 is added. 12x12-13x13 is small enough that strategic moves cannot be played.