3 worms per player, or 1 if the map has no plop holes. Don't forget to enable /rs. All games are bo1. (There will probably be x-ways.)
Teleport your worms at the start. Rope (the direction doesn't matter) around the map as long and fast as you can and count the number of laps finished (having a careful spectator counting laps would be nice). A lap is finished if you passed the Start line.
First players (this will be decided during the tournament, according to how many players there are in each group for example) reaching 20 laps win. The game ends when everyone played the same amount of turns.
If you plop your worm, the current lap doesn't count. If you plop all your worms, you lost.
If a draw happens (i.e. if two players needed the same number of turns to finish their 20 laps, but only one can proceed), replay a game for the players affected by it: the winner is the first one who accomplished 10 laps. If a draw happens again, then it's sudden death: keep playing until someone gets slower than the other (giving both players the same number of turns).
(Description based on Random00's Wascar tournament that took place in 2008.)