The largest scale at which Gor can be played is the battle between the higher powers at work within the solar system, the Kur and the Priest Kings.
Both forces are extremely high tech and the monstrous Kur are only held back from taking Gor (and the Earth, which they desire less) by the presence and power of the Priest Kings whose technology is even more impressive.
The Kur have tried many times to infiltrate Gor and have failed at each turn, often thanks to the efforts of their agents – such as Tarl Cabot – and other times by chance or luck. They have raised armies of ‘native’ Kur, tried missile bombardments, invasions of the inner solar system, setting the cities against one another, trying to starve nations, set up bases in remote regions and even smuggle piecemeal war machines onto the planet.
Despite all this, they have – as yet – been unable to make any true progress in their attempts to conquer, but having traveled so far to claim a new home, they are unwilling to give up.
Intrigues also occur on Earth with both agents of Kur and the Priest Kings seemingly fighting a war of espionage on the surface of that world and also claiming slaves from amongst Earth’s populace to transport to Gor. The Kur, in particular, seem to favour training agents from the Earth – especially women – to lead their operations on Gor as well as transporting large number of Earth slaves to Gor to be sold in order to finance their operations there, landing stealth ships in remote locations to avoid the wrath of the Priest Kings.
The presence of the Kur and Priest Kings introduces a more fantastical and higher stakes element to adventures as well as potentially extending the action to Earth and the steel worlds of the Kur (space habitats hidden around Jupiter, Saturn and the asteroid belt). It is strongly suggested in the books that Earth governments, companies and even educational establishments are in cahoots with one or both alien forces and have hidden knowledge of these alien species and their technology. It’s also strongly suggested that the Gorean slave trade ties into the underground human trafficking networks on Earth.
This would make a great ‘in’ for Earth characters – male and female – to get tangled up in the cold war between the Kur and Priest Kings and transported to Gor. People whose moral and social ethics are wildly at odds with that world, making for interesting conflict and adventure.