'Designers & Dragons' RPG Historian Shannon Appelcline writes:
Not every company in the industry works regularly with others. ICE is an example of a company that largely went their own way, focused on their Middle-earth license and their Rolemaster system, while Hero Games regularly teamed up with other companies in the '80s (and even joined ICE!). But it's possible that Chaosium may be the company in the industry with the most personal connections, thanks to its generous licensing in the early days, and due to a variety of factors since...
...Though Chaosium has at times been small, their effect on the industry as a whole is quite large (and that surely misses dozens of more distant connections).It's quite possible that only TSR (through its creation of the industry) and Wizards of the Coast (through the OGL) have interacted with more companies.
And with Chaosium newly revived and producing more and better material than they have in decades, and with almost all of their properties returned home for the first time since 1984, it's quite possible that they may have a new golden age of connections before it.
Or, as one commenter put it, Chaosium is "The Velvet Underground of RPGs".
"The Velvet Underground of RPGs" Advanced Designers & Dragons maps out Chaosium's interactions with the RPG industry over the decades...
Though Chaosium has at times been small, their effect on the industry as a whole is quite large