Tile Go and Cushion Go: using tiles to remove cycles

luigi · #1

Tile Go is a finite Go variant without superko rules. It differs from Go in the following aspects:

If the last placement (regardless of color) was made in enemy territory and you want to place a stone on your turn, you must first place a tile on an empty point and then, on the same turn, place your stone onto the tile. An enemy territory is an empty area connected only to enemy stones.
You cannot make a placement that would require you to place a tile on a point that already contains a tile. Placing a stone on an existing tile is allowed. Tiles are never removed, but stones on tiles can be captured as usual.
Passing is not allowed, but you can return a previously taken enemy prisoner instead of placing a stone on the board. If you have no moves available on your turn, you lose. This is the prisoner return rule.

Suicide is not allowed. The ko rule is used, but not the superko rule. Cycles, both forced and cooperative, are impossible.

Cushion Go is the same as Tile Go, except you only place a tile when the last placement and your current placement are both in enemy territory. This more lenient rule makes all known Go forced cycles impossible, but does not eliminate cooperative cycles. In return, it keeps the game extremely close to Go. You can expect to place a couple of tiles per game, but this is usually not enough to render any Go moves illegal.

Depicted below is the final position of the longest known high-level Go game as recreated (legally) under Cushion Go rules. The game lasted 417 moves. Only four tiles (marked with red circles) were needed, and the first tile was placed on move 298. For comparison, you can replay the game under Tile Go rules here.

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | . X . X . O X X O . O O X . . O . O . | $$ | X . X X X X X O O O . . O . O . O O O | $$ | . . X O O O O O O . . O . O O X O X O | $$ | X . . X O X O X O , O O O O O O X X X | $$ | . . . X X X O X O . . . O O X X X X X | $$ | X . X X . O X X O O O O X X O X . X . | $$ | X X . X . O O X X X O O O X O . X X X | $$ | X . X . O O X X X X X O X X . O O X B | $$ | C X X X X O X . . X O X . X X . X O X | $$ | X . X X O O W X X O O . X O X X X O O | $$ | O X X O . O . O X X X X O O O X O B O | $$ | O O X O O O O O O X . X . O X O O . O | $$ | O . O X X O O X X X . X . O X X O O . | $$ | . O O . X X X . X O X X O O X X X O O | $$ | O . O O O X . X O O O X O X . X X O X | $$ | . O X , X O X X X O . O O X X X X X X | $$ | O X X X X O O X O O O . O X . X O O . | $$ | . O O . . X O O . O . O . O X . X X . | $$ | O . O . . O . . O . O . O O O X . X . | $$ +---------------------------------------+[/go]

luigi · #2

Defeating eternal life in Tile Go and Cushion Go:

Click Here To Show Diagram Code: [go]$$W $$ ------------------------------------------------- $$ - . O O X . - . O O X . - . O O X . - . O O X . - $$ - X X O X . - X X O X . - X X O X . - X X O X . - $$ - 1 X O X . - . X O X . - 5 X O X . - . X O X . - $$ - O X O X . - 3 X O X . - O X O X . - 7 X O X . - $$ - 2 O O X . - . O O X . - 6 O O X . - . O O X . - $$ - X O X . . - B O X . . - B O X . . - C O X . . - $$ - O X . X . - O X . X . - O X . X . - O X . X . - $$ - . X . . . - . X . . . - . X . . . - . X . . . - $$ - . . . . . - . . . . . - . . . . . - . . . . . - $$ -------------------------------------------------[/go]

After

, Black places a tile and a stone at :bc:

. After the incursion :w7:

, Black cannot place on the tile ( :ec:

), so Black dies.

rhwocns · #3

luigi wrote: