Does this game ever end or can you keep playing until you've become the leader of every guild or something like that? Like how most games have a main quest but you can keep playing after you've finished the story.
There aren't very many, actually. Theres the College of Winterhold, a magic "guild". Then there's the Theives Guild, self explanatory. Then the Dark Brotherhood, which is a group of assassins. The companions let you become a werewolf, they're a "brawling guild". Then there are the Imperials and Stormcloaks, different side of an ongoing Civil War. You can become the leader of the first 4 I mentioned, you can become pretty high up in the other two. I might have forgot some, but I'm pretty sure that's it.