John Welford already mentioned rugby, where gridiron football evolved from. Yet it seems so inconceivable that those thinkers from the 1800s wanting to improve on rugby would have come up with this game of four downs to move a weird-shaped ball 10 yards. Who thought of that? Rugby has players moving constantly.
Canadians have adopted gridiron football as well. The Canadian Football League is so strange in that Canadian cities compete to see which city has the best Americans. There's a little rule that each Canadian team has to have about 20% Canadians on it. Without that rule, it would be all American. Yet Canadians put their kids into this sport knowing full well the chance of their kids turning pro are very small.
Football has many more rules than rugby.
Baseball is another American sport with a plethora of rules. Baseball came from cricket, but that was a sport with too many rules to start with. I tried to figure this game out, but it is just as bad as baseball. One wonders who invents these games?
Hockey, basketball, rugby, lacrosse, soccer, etc. have a simple objective that many people can easily understand.
The next American sport will the one with even more complex rules. Maybe rollerball will finally go big time:
