My Empire of Arn campaign world is full of gates. Gates leading to other planes, others planets, other universes. For most of Arn's life, these gates have lead to other places within my own multiverse. However, that wasn't the reason these gates were originally there. They were there so players could bring their characters from other campaigns into and out of my Arn campaign.
While moving characters from one GM's campaign to another is uncommon today, it was relatively common in some parts of the country in the mid to late 1970s. By 1980, the practice had already started to die out, as Lee Gold (editor of the rpg APA Alarums & Excursions since 1975 or so) laments to a writer of in an article in the August 1980 issue of New West magazine, "It's Only A Game...Or Is It?":
...Gold sees communication between the different games systems gradually breaking down, as the increasing differentiation of rules, worlds and cultures leads to incompatibility. "San Francisco runs 'high entropy' worlds - lots of magic and power; Long Beach and Boston, 'low entropy'. RuneQuest is talking strike rank; D&D is talking dexterity rolls. They can't talk to each other. It's like the Tower of Babel," she says. Characters can no longer adventure freely from one world to another, as they could in the early, simpler days of FRP, from Arduin to Mistigar, for instance, without severe culture shock. "The trend," Gold says with the regret one feels for the collapse of Camelot's Round Table, "is to closed-world campaigns.As far as I can tell, this style of play started in California and spread to areas of the country with a lot of fannish contact with California. I heard of it from running into someone who played in Deanna Sue White Mistigar campaign at a SF convention. I thought it was a wonderful idea and bought it back to first my college gaming groups and then to groups I gamed with in the San Antonio area. This is when Arn got all its gates.
Moving characters back and forth between campaigns wasn't all that hard back then. The rules for D&D and AD&D were fairly simple. Characters with weird powers or magical treasure that was too powerful for the world their were visiting just discovered that their items or powers did not work as well in the campaign world they were visiting because "its natural laws were different." Conversely, a character who was too weak for a high-powered campaign world he was visiting might discover that his Mace +1 functioned as a Mace +3, +5 vs Undead in that high-powered world due to, again, the fact that "its natural laws were different."
Sadly, with the proliferation of different rule-sets and the move to more story-centered campaigns, the practice of players being able to move their characters from one DM's campaign to another had pretty much died out by the mid-1980s. By then, the gates on Arn mainly brought NPCs and monsters from other parts of the my own multiverse instead of visiting PCs. But every once in a while, the gates fill their original purpose and bring in a PC from another campaign for a visit -- usually the character for a friend from across the country visiting one of my regular players for a week or two. For the last 10-15 years, it always surprises people that I will allow this. Many of the players who have benefited from Arn's gates in the last 15 years, have never heard of another GM who will allow this. This always saddens me and makes me nostalgic for the time when travel between campaigns was common.
Through the door there came familiar laughter
I saw your face and heard you call my name
Oh, my friend, we're older but no wiser
For in our hearts the dreams are still the same...
Those were the days, my friend
We thought they'd never end
We'd sing and dance forever and a day
We'd live the life we choose
We'd fight and never lose
Those were the days
Oh, yes, those were the days