An MMO with multiple servers. Each server will have different gameplay modes, and to get to a server you will have to meet certain requirements. As a few examples, a Battlestar Galactica (Re-imagined series) server, would include space battles with realistic physics, choice between factions (humanoid Cylons, centurions, raiders, hybrids, rebel Cylons, and Humans), ground battles (with air support from whoever won the space battle), and dynamic campaign maps (Sneak Attack Nuke). The requirement for this map would be age, because staying close to the show would require "Things", and if you don't know what those "Things" are, watch the show.
A zombie survival game with Zombie Survival Guide style zombies, where you play as a person after the zombie outbreak. this server will have different sub-servers taking place in different time periods. Time periods include the Roman Empire, Medieval age, 1950's, and modern. The server will include the whole planet, thus limiting it to my imagination, because no computer can run 6534942 AI's simultaneously After all zombie or human life is wiped out, the era will restart with a random person. Zombies will be AI controlled, because nobody wants a zombie hacker. You should fortify an area and go out during the day, because Human night vision is poor. Eating and drinking is required, because otherwise people could sit in a tank and hide forever. The requirement for this server is "dedication", by which we mean addiction.
The third example of a server would be like "Starship Troopers". For Humans gameplay will be an FPS,with the standard mix of assault rifles, shotguns, sniper rifles, grenades, and handheld nuke launchers. Human players who do well unlock better weapons and armor, such as the suit in the third movie. Alien players will experience more of a third person fighting game, with the claws having the same effectiveness as in the films, and killstreaks unlocking the ability to temporarily become a better alien (Like the movie's Juggernaut, which is an acid/fire/etc. breathing tank).
The fourth example for a server is a Warhammer 40000 version of the Sims!
Can anyone else tell that I have a short attention span?