Tile Go

Tile Go is a finite Go variant without superko rules. It was invented by Luis Bolaños Mures in July 2023. Tile Go differs from Go in the following aspects:

• If the last placement (regardless of color) was an incursion and you want to place a stone on your turn, you must first place a neutral tile on an empty point and then, on the same turn, place your stone onto the tile. An incursion is a placement in enemy territory. 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. (For greater flexibility, stacking up to N tiles on the same point can be allowed.)
• 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 from Mathematical Go. Standard Go scoring is also possible.)

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

The diagram on the left shows the final position of the longest known high-level Go game as recreated under Tile Go rules with unrestricted tile stack height. The game lasted 417 moves. There are 74 one-tile stacks (), 5 two-tile stacks () and 1 three-tile stack (), and the first two-tile stack was created on move 354. You can replay the game here.

Cushion Go is the same as Tile Go, except you only place a tile when the last placement and your current placement are both incursions. 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.

Example