The reason this particular variant ties in well is that a single stone handicap in Pente and several variants is basically a meaningless stone, since it would not affect the outcome of games played in the variant. Some variants would be affected by a single stone handicap, but others, including Pente would not - until now...
In +/- Pente there are two phases to each player's turn - Phase 1: playing a stone onto the board as usual in whatever variant is being played Phase 2: (optional) removing a single stone of one's own which one has played onto the board from the board and adding that stone to one's opponent's captured stones. Most games would play out as they have been played out in the database, but there are occasional times in a game where a placed stone has been a necessary part of play in the game, but then that same stone later becomes a (sometimes game losing) liability. In such cases, one would be able to remove the liability stone from play at the cost of adding it to the stone count of one's opponent. In a game in which that opponent already has a single stone handicap, that player now has a pair of stones which they would not have otherwise had at that point in the game in conventional rules Pente. An example game (currently still in progress as I write this) in which I would (if possible) remove a stone of mine from the board and add it to my opponent's capture count is this Poof Pente game: https://pente.org/gameServer/tb/game?gid=50000000197636&command=load&mobile&w=451&h=301 where I would remove, if possible, the stone at L11 on move 18.
Retired from TB Pente, but still playing live games & exploring variants like D, poof and boat
Re: +/- Pente and variants
Posted:
Nov 13, 2017, 3:27 PM
Should a player be allowed to make a move in the + phase and then take that just made move away in the - phase? I think either way would be a viable way to play the variant, with the "allowed" version making it possible to pass in a position (which would likely never be a necessary option in Pente, but would be useful in anti Pente) as in Go, particularly with AGA rules. More significantly, however is the an additional flexible (and generally safer) option in the ability to capture stones without having your stone which makes the capture immediately recaptured along with a second stone. In -/+ Pente only the second stone for a potential recapture can be removed from the board during the same turn as a capture is made, but in +/- Pente a capture could be made by playing a stone and either the stone just played or the other stone which would make the stone just played vulnerable to being recaptured could be removed from the board and placed in one's opponent's capture pile. As far as I can tell, this difference (removing the stone you've just played) is the only one of significance between having the subtract a stone from the board phase precede the add a stone to the board phase versus the way the rules were stated above. Therefore, both variations could be tried and if the +/- Pente option proved to be too radical a change, the milder -/+ version could be used instead. Below is an example game in which the game could be prolonged for a few more moves with the removal of the N15 stone at move 20. With the captures at 9-8, P1 then has to play precisely and avoid creating attackable pairs while creating a winning threat.