There are also UCL sets and great (World Cup) squads and World Cup sets, but they seem to be based on the small samples of just the year's competition itself, so I do not trust them or see the point. (COVID did mess some things up, admittedly, so how much of this is an aberration is an open question.) They have, over time, offered complete sets of seasons from Europe's main leagues plus MLS, but some have not sold particularly well and have been dropped from the catalog over time. I think the game comes with the UEFA Champions League semifinal teams from the year before. There are basic rules and optional ones, and Mark has done yeoman's work tinkering with things to improve its playability, but if you are not one who enjoys getting under the hood, you certainly don't have to. It does a pretty decent job of approximating the feel and flow of soccer, though, as Mark will tell you, it can use a little customization in places to work better. It has been vastly improved since an awkward launch a decade ago.
