Feel free to ignore this if it's too much.
You are going to run a fantasy game. This isn't going to be any fantasy game, though. This is going to be a fantasy game about your group. A great evil is going to threaten everything you hold dear, and there are only a few heroes who can stop it. These aren't some grand, prettyboy characters who exist to kill goblins and look good. No, these are some kids from a poor neighbourhood who had the guts to stand up to the entire world when no amount of fame or fortune could make anyone else brave enough, when no love or honour could make anyone else care. You're the nobodies that had the steel for a plan and the heart to make it work.
The whole setting is going to be original material. EVERYTHING is going to be handwritten, and everything you use is going to be for this campaign. When you save the world, all the character sheets, all the GM's notes, all the dice, the pencils, the goddamn scratch paper you wrote initiatives on are going in a little box. Along with that, you put a little epitaph for each character, telling how great they were.
None of that leaves the box until somebody dies. When they do, you get together in your little group, and you read that epitaph, and you burn or bury everything about that character. Going into the ground with that humble pine box is a memory. A memory about all those Fridays, all those empty bottles, those critical hits and levels up. It's about Ferrus Victus and the innkeeper back in who-knows-where and the very first level one human fighter you ever played. It's about your friends and all that time together.
And you'll cry. Fucking hero's tears, you'll cry.