Aspiring Lurker (He/Him)
I have watched nearly no Critical Role, so I'll have to trust your description of the game. When I talk about his table being different, though, I'm referring at least as much to the people around it as I am the game they're playing, as well as the stories that emerge.Mercer is a good DM and the players are REALLY game and like to chew scenery - but strip that away and his game is near bog standard D&D 5e.
It's zero to hero, start small (small area, single town) and expand the world from there.
The rules are standard 5e with Nary even a homebrew (he shoehorned in a pathfinder class initially and has introduced more stuff as he goes but mostly classes and items, the rules remain untouched).
This is not a criticism - it's a comment stating anyone who wanted to start their own campaign could use the way he started and expanded his as an easy to follow model.