Tag was a short lived game on the British edition of Whose Line Is It Anyway. This was a game that featured all four contestants. To start the scene, two of the players would each assume an audience suggested position [sitting down, on all fours, standing, etc.] and the performers would work out ideas from their positions. Periodically, one of the performers off stage would yell, "Freeze!" and tag one of the performers and assume their position. The performers were not static during the playing and moved from the initial positions. It's sort of a hybrid between Props and Living Scenery if that gives one a better picture.