So I’ve always been a fan of microhistory in fictional universes; a series spanning a long time period focussing on a central cast or location and showing its progression through time.
Assassin’s Creed has the potential to explore this but shifts both period and location with each game.The only notable example is Monteriggioni in modern day in AC: Brotherhood.
Another good candidate for this are the Rockstar games. Grand Theft Auto has a vaguely shared universe between games, but a moment ago I realised they could do a lot more with this. Imagine Red Dead, LA Noire and GTA VI all taking place in roughly the same area and a shared universe where we see cities, events and places develop through the late 19th century, the 1940s and modern day? Cities grow, asphalt roads appear, buildings are demolished or renovated, families grow and gain or loose influence, etc.
Whatcha think? ^^