In a comment over on Doc Rotwang!'s blog I mentioned that I keep a mental list of settings alternatives to Vanth, the sample setting for Encounter Critical. I'm not good at keeping mental lists (just ask my wife) so I decided that it was probably time for me to record it somewhere.
Any other kitchen sink gameworld
This one's a no-brainer. The setting material of Rifts and the World of Synnibarr could both be playable under EC with a little work. The various mini-settings provided as examples in Tom Moldvay's Lords of Creation could be used individually or as part of a universe-hopping campaign as intended. Indeed, I don't see any reason why my own Lords of Awesome run couldn't have been played under Encounter Critical rules. Counte Dante wouldn't have suddenly become a trapeze artist, but otherwise the adventure pretty much stands as written.)
An awesome mini-setting found in issue number 1 of Pyramid magazine, back from when it was a print venture. The whole is a small realm apparently in the bowl of a large crater. People from various times and universes find themselves mysteriously transported to the Hole. No one knows why. And no one has ever escaped. Various ramshackle societies have been built by the unwilling emigres to the Hole. It's sort of like an Al Amarja/Riverworld mash-up. Very keen. You can get access to The Hole by tracking down the original issue, subscribing to the online version of Pyramid (or so I'm told), or buying GURPS Best of Pyramid volume 2.
The Gilligan Islands
When I first read them mention of headhunters in the description of the Warrior profession I knew exactly what Hank Riley was talking about. As a wee lad Star Trek was the only show I liked better than Gilligan's Island. Note that I am not talking about simply "Gilligan's Island" but rather the Gilligan Islands, the aggregate of all the crazy stuff that did or can take place in and around the setting of the TV show. One island of this mythical archipelago still has Japanese troops fighting World War II, others host mad scientists or swarthy commies or crashed astronauts or whatever. In essence, it's the Bermuda Triangle of the Pacific.
Revolt on Antares
This TSR minigame of space operatics is the bee's very knees. And it is rife with interesting characters, political factions, and ancient alien artifacts. Will the PCs align with the Imperial governor, or one of the psionic families? Is an uprising of the nonhuman natives in the works, or an invasion by the tentacled Silakka? And could there be any galactic heroes that are cooler than Doctor Death, the battlefield zombiemaker, or the Nullspace Kid?
Thundarr the Barbarian
Show me another show that features Conan with a light sabre fighting alongside a magic princess and an angry wooky against mutant wizards and I will TOTALLY WATCH THAT CARTOON.
That's a robot GI and Universal Studios monster commandos taking off into space with crazy ass writer Bob Kanigher. Or maybe the guy with the pipe is actually J.R. "Bob" Dobbs. Either way it works. It totally works.