"Capture Pentominoes" is an abstract board game based on the 12 pentominoes. In the standard "Pentominoes" game, two players take turns placing pentominoes on the board, one at a time. The last player able to place a pentomino is the winner. (In miséré pentominoes, the last player able to place a pentomino loses.)
In "Capture Pentominoes," the same basic rules apply: the players alternate placing pieces on the board, and the last player to move wins. However, as the name of the game implies, it also introduces the idea of "capturing."
Often a player will place a new pentomino on the board so that it shares part of its perimeter with another (older, already placed) pentomino. If the shared perimeter is three square-sides or more, then the older pentomino is captured, and the player marks it with one of his tokens. Notice that a newly placed pentomino is never owned by either player.
It is possible for a player to capture a pentomino that his opponent has already captured. In such a case, the opponent's token is removed and the new player's token replaces it; only one player can own any given piece at one time.
On his turn, before placing a piece, a player may remove from the board as many of his own captured pentominoes as he pleases, thereby opening up space for him to play new pieces. However, the pieces he removes are not immediately available for him to play elsewhere on the board. They remain "out of play" until his opponent's turn.
As stated above, the last player to have a legal move is the winner.
The game of "Capture Pentominoes" can be played on any size or shape of grid. However, a 7-by-7 grid seems to work very well; on that grid, typically each player has a choice of five different pentominoes on his turn.
This C program uses a simple alpha-beta lookahead to play "Capture Pentominoes" on a 7-by-7 grid. Extension of the core to deal with non-rectangular grids, an early-game analyzer, or more intelligent lookahead is left as an exercise for the reader.
As far as I know, "Capture Pentominoes" is a totally original concept — at least, as totally original as any board game based on commonly known basic elements can be! So please don't try to go and copyright it yourself, or sell a boxed version for $29.95, or things like that. But please do play it, experiment with it, solve it, or whatever you feel like. I don't claim to control it any more than I claim to control poker. I just get to say I'm the discoverer, that's all.
I actually came up with the game back in August 2003, before I made this post to rec.games.abstract, introducing the game. Following a suggestion on the newsgroup, I spent a few months fiddling with the now-defunct Gtkboard, but never got as far as a working version of "Capture Pentominoes." The "interface demo" that resulted is still on the Gtkboard site, here.