It’s been noted in a million outlets that association football is truly the world sport. The rules are easy to learn, the play is straightforward (not that there isn’t a lot of strategy in how high-level games are played), and it can be played just about everywhere. On the other hand, the most popular US sports, gridiron football and baseball, have much more limited audiences and—coincidentally or not—many, many more rules. I like both of these sports and still couldn’t give an exhaustive summary of the rules.
What’s interesting is that the only US sport to really catch on globally is basketball, which is a lot more like association football than gridiron football and baseball. There are more (and more complicated) rules in basketball than in association football, but less than in the other big US sports, especially in the early years of the sport.
This may not be remarkable except that I’ve heard from more than one non-US person that we Americans seem to them to be fixated on rules. Do we like our professional sports to be more structured because we just think about rules more in general?