Hip is a game invented by the mathematician Martin Gardner.
Setup
The game is played on a NxN square. The board starts empty
Move
Each player place stone on any unoccupied square.
The goal is to avoid completing any square by marking all 4 corners with stone on the same color.
The square may be any size and tipped at any angle.
On 6x6 board there is 105 such squares.
The n x n board has n * n * (n * n - 1) / 12 squares.
The first player to complete a square is the loser.
Variants
Classic Hip is solved game - the second player is winner.
To win 2nd player need play the reflection of the 1st player's moves.
There are different ways io avoid this problem.
Double-Move Hip
This variant was designed by
Mark Thompson
In Double-Move Hip ach move consists of placing two stones onto the board,
except the first player's first move.
In this way neither player has a clear advantage.
Odd sized boards
Play on odd sized boards, with a center cell where
the 2nd player cannot continue to use the mirror strategy.