Copyright (c) 1985 DMR Games

Kassle is played on an empty 5x5 square board:

DROP - A player, on his turn, can drop a stone on an empty cell.
SHIFT - Instead of dropping a stone, the player may decide to shift one row or column, one cell left/right (for rows) or up/down (for columns).
All stones are shifted on the chosen direction. If a stone is shifted off-board, it is placed on the other end of the shifted row/column (so, for shift purposes, the board is a Torus).
KO rule- If a player has just shifted, the next player cannot shift that row/column.
GOAL - A player wins when he makes a 5 in-a-row (orthogonal or diagonal).
If a shift give both players a 5 in-a-row, wins the player that made that shift.

An example

White to play. He shifts the 'a' column down, making a 5 in-a-row and winning, even if Black also makes a 5 in-a-row.