L-game is a beautifully simple game invented by Edward de Bono. Despite its basic rules and small playing area is has some surprisingly complex strategy.
The game is played on a 4 by 4 grid. Each player has an L-shaped piece which covers four squares of the grid. There are also two neutral circular counters which cover one square each.
The starting position is shown below.
oWW. W: White L-piece
.BW. B: Black L-piece
.BW. o: Neutral counter
.BBo .: Unoccupied square
Players move in turn. First, a player must move their L-piece to a different position on the grid. Rotating the L-piece is allowed, as is turning it upside down. Once this has been done, the player then has the option of moving one of the neutral counters. Play then passes to the other player.
A player loses the game if they cannot move their L-piece.
There are fifteen winning positions which are shown below.
.B.. .o.. ..o. ..B. ..B.
oB.. oB.. oB.. o.B. o.B.
WBBo WBBB WBBB WBB. WBBo
WWW. WWW. WWW. WWWo WWW.
..B. .... ...o ..o. .o..
o.B. BBBo BBB. BBB. o..B
WoBB W.B. W.B. W.B. WBBB
WWW. WWWo WWWo WWWo WWW.
..o. ..B. .B.. ..B. ....
o..B BBB. .Bo. BBB. oBBB
WBBB W.o. BBWo WWWo WWWB
WWW. WWWo WWW. W.o. W.o.
In each of these positions the white piece cannot move. Note that none of the winning positions have the white piece in the centre of the board, and twelve of the fifteen positions involve the white piece being placed in a corner.
This is the key to L-game: one must try and force the opponent to play into a corner, while keeping one's own L-piece in the centre. If your L-piece is in the centre, then it has many options and it is unlikely that your opponent can force a win.
Skilful use of the neutral counters is very important, since they can be used to force the other player into certain moves on the following turn. They can also be used to stop the other player from being able to play his L-piece into a winning position.
Between experienced players the game is almost always a draw.