Equipment: Tennis court or similarly marked out area with lines on the floor.
This form of Tag is more for taking advantage of playing in an area where you already have court lines drawn out, rather than deliberately creating them for the game.
One or two players are appointed as catchers and choose a position on the lines. All other players can take up positions anywhere else they like along the lines marking out the court or playing area. All those playing can only run along the lines.
Decide if those caught have to leave the court and stand to the side, or have to stand where they were caught and be an obstacle in the path. Players can release those who are caught in order to free up that line again. If you want to make it difficult, players can only free a captured/tagged player by going through their legs (as in stuck-in-the-mud)