A Recycler Campaign refers to a role playing campaign where the setting is ammenable to importing characters from previous games.
Some game worlds and campaigns have a tight and careful interaction of characters, history and events. Characters must be organic to this setting and it's context in order to function properly.
Some Game Masters just dislike allowing characters from games they did not GM.
Then there's me.
As a player, I like my characters. I hug them and squeeze them and call them George.
It's not unusual for campaigns to end prematurely. When this happens I feel let down. I don't get to "finish" playing the character through to what feels like a natural and satisfying end.
When I have a game world that will tolerate characters "Coming in from out of town", and one where the framing mechanism is generic enough to be flexible, then I will invite players to bring in characters from other, unfinished games. This allows a player to continue playing a character he has affection for.
The hardest part of a recycler game is balancing it. Frequently characters who are well liked have been played to high levels. This makes balancing them with other characters and a new story in a new game world difficult.
A recycler game can be great fun when it works. At least of one my best games started this way... before endng prematurely, stranding characters in an unresolved state....
Well, perhaps next time.