Crusader Kings 2 models the hopes, jealousies and paranoid plotting of around 30,000 unique actors, scattered throughout the troubled hierarchies of medieval Europe. From their varying positions of power, they marry, breed, wage wars and bump each other off with splendid selfishness. It's a pioneering sort of grand strategy soap opera, and it's about to get thousands of extra cast members.

CK2's sixth expansion, Rajas of India, will grow the map by 50% and add 400 new provinces, each with their own cabal of commanders, advisers, vassals children to be traded for political advantage. The rulers of India are mapped to three regional religions, which convey unique socio-economic boons upon their adherents, affecting their war-readiness, stability, and research competence. There's a new set of regional events to reflect the local festivities of the era, new jungle terrain and, inevitably, war elephants. It's plenty to be getting on with, but the most impressive thing about the expansion so far is how much of it Paradox are giving away for free.

That massive map increase will be free to everyone with a copy of CK2, for example. You won't be able to play as the new leaders and factions, but you will be able to meet, barter with and assassinate them. The free update also expands Africa with additions to Abyssinia and Nubia - the remnants of a planned future mini-expack that the designers decided to release as a bonus. That's in addition to Steam Workshop support, Steam multiplayer support, and smaller fixes that the CK2 community have been asking for, like a borderless windowed mode.

Evidently, Paradox are keen to keep their players playing - it's one of the reasons they love making big, brainy sandbox strategy games with lots of replayability. The free stuff encourages further playthroughs, which encourages more stories, which are inevitably shared online, creating a positive wave of word-of-mouth endorsement from which Crusader Kings 2 has particularly benefited. "We want to maintain interest in this game," says designer Henrik Fåhraeus, "keep it alive, keep it evolving and see what we can do with it."

India was a natural evolution for CK2, he explains. The feudal systems of medieval Europe fit comfortably with India's politics at the time, which made it easier to adapt existing systems to the new nation. There are differences, of course. The expansion should offer a more stable and peaceful starting scenario than central Europe. "The really cool thing about India is that it's such a pluralistic and tolerant society for its time," says Fåhraeus. "Even in these medieval times with the holy warring going on in the rest of the world, these three old religions of india, the Jain, the Buddhists and the Hindus. They were used to living together, and had been living together for a thousand years, basically, in more-or-less peace."

The Nair are the most peaceful of all. Harmonious internal relations make up for a lack of battle-nous. Hindu territories, meanwhile, are good in a ruck and have access to a wide range of creative Cassus Belli (land and title claims that are used to instigate wars), but are hampered internally by the warrior caste's relationship with the ruling classes. Buddhism's progressive musings on the nature of the soul and infinity manifests as a potent research boost that'll let you grow your society quickly.

To reflect India's tolerant nature, you'll be able to flit between religions more easily than the vanilla game. "I might want to start out as a Hindu ruler and conquer stuff," Fåhraeus suggests, "and then I switch over to become a Buddhist to research, and I might end up with the Jain to have a peaceful, stable realm, so my vassals love me."

The Buddhist belief system also introduces reincarnation, a particularly interesting addition given CK2's focus on succession. "I want to do really cool things about reincarnation, but I'm not sure how much we're going to be able to do," Fåhraeus says.

"I want a kid to be born, and people will think he's the reincarnation of a previous ruler, probably one of the better ones, and then maybe he will actually take on some of those personality traits."

I ask if there will be room for players to fabricate reincarnation claims to bestow advantage on your offspring, but the team are worried about presenting the concept in such cynical, power-grabbing terms. "It's a little bit dangerous, we're always stepping on toes. Hindus and Buddhists take this really seriously. I'm not sure if we want to do that."

CK2's rapid expansion - compounded by fantastic community mods - makes it an all-consuming pastime for avid fans. It was a tremendous story generator on release way back in 2012, and all the expansions have had to do is add neat new story beats to play with. Rajas of India's religions should do that nicely, and the extra map space will only make the formerly-squashed Eastern factions more viable. It's out in Spring.