Copyright (c) 1970 Sidney Sackson, Hoyle Publ.

Tempo is played on the following 5x6 square board.

MOVE - A player moves one of his stones that it is in the middle of a (diagonal or orthogonal) 3 in-a-row made by stones of either color. Then the stone may slide any number of empty cells in one of the two perpendicular directions of the 3 in-a-row it belongs.
CAPTURE - A sliding stone can stop on a cell occupied by an enemy stone, capturing it.
CORNERS - A stone on a corner may move if it is orthogonally adjacent to two other stones. It may slide (and capture) in the only possible diagonal direction.
GOAL - A player that is unable to move loses the game.
If a situation arises where both players repeat a board position, wins the one with the least number of stones. If both have an equal number of stones, the game is a draw.
Some examples

The marked black stone can move to one of the green cells and can also capture the marked white stone.

The white stone on the top-right corner can slide diagonally one, two or three cells.