Weird characters are encouraged, and as long as it is somewhat balanced, races and classes of all kinds are allowed (though this may run the characters into problems if they materialize in 17th century Europe with a half-orc, a robot, and a zombie).
In order to maintain an element of player choice, characters are allowed to pick from at least 2 possible missions that are given to them by their superiors. These missions may be adventures written by oneself, or modules taken from elsewhere. Its not important to make the adventures fit into the campaign world, since the campaign world is every single world. Adventures begin with a briefing of what the party has to acquire, along with relevant information about the world they will be adventuring in, followed by the party being dropped off on that world near the adventuring location.
I'm kind of in love with this idea, and if I were to run a drop in drop out game via discord I probably would run something like this. It is the ultimate deterrent for GM burnout, since every single adventure can be fresh and exciting!
Possible ideas for adventures using this set-up:
- Acquire an anti-matter energy cell from the wreck of a gigantic spacecraft.
- Kill Count Dracula and drain him of his blood, to sell on the black market.
- Enter into the 666th goblin olympic games and win a gold medal, or conduct a heist to steal the medals.
- Capture a live larva of the daemon sultan Azathoth.
- Travel to the bowels of the Earth and steal the planet's soul from the angels that guard it.
- Survive the tomb of horrors and steal Acererak. Just put him in a box or something.
- Infiltrate the Carcossan masquerade ball and steal the pallid mask.
- Travel to the dawn of time and find out which came first; the chicken or the egg?