L game

The L game is a simple abstract strategy board game invented by Edward de Bono and introduced in his 1967 book The Five-Day Course in Thinking, designed by de Bono partly to illustrate that a game does not need complicated rules or a large board to require genuine strategic thought. It is played on a small four by four grid, on which each of the two players controls one L-shaped piece covering four squares in the shape of a three by two tetromino, alongside two additional one by one neutral pieces shared by both players. On each turn a player must first move their own L piece to a new position on the board, which may involve rotating or flipping the piece over, provided the new position differs from where it started and does not overlap the other player's L piece or either neutral piece; having moved the L piece, the player may then optionally relocate either one of the two neutral pieces to any empty square. A player loses when it becomes their turn and there is no legal position remaining to which they can move their L piece, and despite the board's small size and the game's few rules, expert analysis has shown the game has been completely solved and rewards precise positional play.