It’s funny, I’ve always been a big fan of Larry Niven and computer strategy games like Master of Orion, but I’ve never considered combining the two until just now, and the more I think about it the more it seems like a great idea. Please, someone steal it from me, I’ll buy it when it comes out.
The setting allows a good number of playable races - not a huge number, but having fewer allows you to customize them more. I think it should be humans, kzinti, trinocs, and that hard to pronounce blind race that were a kzinti slave race for a while. Maybe puppeteers too, this may sound strange but I think it might work.
The gameplay would be similar to Master of Orion, you would take control of the homeworld of one of the races (or it’s several planets if you were playing a scenario that takes place when your race has them) and be in charge of what they researched, what they built, etc. The technology tree would be significantly expanded, though, somewhat like the one in Hearts of Iron, which has you researching not just new weapons, but technological advances and theories that lead to future advances, as well as doctrines, which are basically strategies that allow you to use certain kinds of technology more effectively. The doctrine system is what I think would make a game with such diverse races work and still be balanced. The puppeteers could be an incredibly wealthy race with high production and high technology, but kept in check by denying them any military skill at all, except defensively. This would force the player to play the puppeteers as they were in the stories - manipulative traders who never expanded beyond their first 5 worlds. They would be given doctrines to give their race the ability to deal with crowding, which would allow them to build a lot more population onto a planet than the kzinti can manage (who can only fit about a billion kzin on a planet before they start killing each other). You could start humans as medium-low tech in some ways but with but at their first hostile encounter give them the ‘Kzinti Lesson’ doctrine, that allows them to use the reaction drives of their ships as very effective weapons. This would give them the chance to hold off the kzin until they could research and steal enough technology to be their equals. If this happened to lead to the humans overrunning and enslaving or exterminating the kzinti, well, that’s the kind of alternate universe that can happen in these games (i.e. the Mexican-American War of 1942 in my current campaign in Hearts of Iron).
Diplomacy would have to be a big part of the game. It would have to have an option to force a race to totally disarm for a period of time after beating them in war, so you could recreate the situation for middle-period kzinti or the human colonies when the kzinti took them over. In fact, it would be a good idea to make it so that certain kinds of governments had to stop conquest if the losing side surrenders and offers to disarm for a certain period of time.
Anyway, that’s my idea, there’s a lot more to it but I have to go to work soon.