Tennis polo
The sport is played on a grass field between 80 and 100 yards long and 50 to 65 yards wide. The goal area is a semicircular line with an 11-yard radius and the penalty mark at 13 yards from the goal. An experimental rule has a second semicircular line on the field with a 17-yard radius. Generally, a field for gridiron football or soccer can be used.
List of gridiron football rules
The first major indoor football game was the 1932 NFL Playoff Game, which was played indoors in the Chicago Stadium due to a severe blizzard that prevented playing the game outside. A dirt floor was brought in, and to compensate for the 80-yard length of the field, the teams' positions were reset back twenty yards upon crossing midfield.
Two rule changes appear to be inspired by Canadian football rules:Field Size – 50 yards long by 25 yards wide, with end zones a minimum of 5 yards in depth. Fields may vary in size due to physical constraints within facility, with CIFL permission. End zones may be rounded due to hockey board configurations. Padded dasher board walls around the entire field that act as an extension of the ground (only "out of bounds" if contact made by opposing player that forces player into the dasher wall, much like a ‘down by contact’ rule).