Both players take turns placing their seven pieces on the board one by one.
After that a piece may move one position orthogonally. It may capture by approach: after it moves, an enemy piece (or an unbroken string of enemy pieces) adjacent to it along its line of movement are taken. It may instead capture by withdrawal: if it begins its move adjacent to an enemy piece (or unbroken string) and moves directly away, the enemy piece(s) are taken.
A piece that just captured may make another capturing move, though it must change directions with every capture and it may not immediately return to the point it just occupied.
Captures are multiple and mandatory.
The object is to capture all of the opponent's men. In case of repetive moves, the player with more pieces on the board wins.

 
Skällviksborg is a castle ruined by war in 1312. It's located near my beloved Norrköping, Sweden.