Two teams, each with the same number of players, play against each other. The red team starts and tries to roll a wooden 'bowl' as close to the target as possible. The blue team then tries to get closer than the red bowl or to knock it out of the way. The winning team is the team whose bowl is closest to the target when all the bowls have been played.
The photo shows how the game works, but was not taken at a bowling alley in Heuvelland.