The most recent, less than Super Bowl notwithstanding, the N.F.L. continues to be a behemoth, dominating the sports landscape in revenue, attendance and television ratings.
That popularity has over the years tempted entrepreneurs to try to cash in by starting professional football leagues of their own. The latest effort is the Alliance of American Football, which plays its first games on Saturday.
There have been plenty of pretenders to the N.F.L.’s crown over the years. None have succeeded, but all had their share of novelty.
World Football League, 1974-75
Season July to December
Weird rules A touchdown was worth seven points; teams could then go for a conversion from scrimmage for one more “action point.” No sudden-death overtime; a full 15-minute quarter was played. No preseason.