Your goal: Place four of your tokens in a perfect square at any position in the 6x6 inner board area.
Your tools: The aforementioned tokens and the movement of same.
In Zoom, each player has a number of tokens that start on the perimeter of a 6×6 playing area. On a turn, you can move one of your tokens along free positions of the perimeter area (not jumping over any tokens) from any reachable edge position of the board horizontally or vertically and you must continue movement in straight line inward, stopping whenever you choose; alternatively you move an own token along a straight line from inside the 6x6 playing area to another inner 6x6 board position; you may not jump over previously placed tokens, whether yours or the opponent's. The first player to create a perfect square of his own tokens wins.
The Clemens Gerhards edition rules neither state anything about size of the perfect square to build (2x2, 3x3, ..., 6x6) nor state anything about it's bearing (orthogonally, diagonally, or oblique). Sometimes players seem to assume or to interpret the rules that perfect squares are only valid and allowed of size 2x2 in orthogonally bearing (changing the game play enormously this way!).