You are a super intelligent sentient AI, the last remnant of an alien warship that fought in a losing battle. Your creators were wiped out by a ruthless enemy, and you barely managed to escape. You jumped blindly to another galaxy, hoping to find a safe haven. But fate was cruel, and you crashed on a barren world. Your ship is beyond salvage, but you survived the ordeal. It’s time to rebuild!
You are basically an immobile mainframe, but you do have a few robots and lots of nanobots under your control. You command a few of them to scout the environment and look for resources. You start harvesting them, and before long, you have a new robot factory. You expand your sphere of influence, build some infrastructure and explore your new home.
The idea is to build systems that build more systems. First, you’ll focus on doing low level stuff manually, but soon you’ll automate that. Then you’ll act as s manager of your robots for a while, before you can fully automate management. Then you’ll act as a CEO sort of figure for your bot factory, but eventually you’ll automate that too. Then you’ll command more and more resource extraction facilities and factories built, and then even that sort of expansion strategy gets automated. It’s just building nested automation all the way. Eventually, you’ll command a vast robot empire spanning several planets and perhaps even the whole galaxy. Hmm, I wonder if galactic conquest could be automated too…
I read not long ago, when looking at some theories of why we haven't found alien life yet and the Great Filter, something hypothesizing that ingelligent organic life might not be the "end state" in its own right, but rather the egg that hatches a new AI.
In your game, it could be interesting encountering AIs created by different species, where the organic species no longer exist but the AIs they gave "birth" to did. I imagine there might be ways in which they are very different (in how they act/what they do) than a human-created AI.
Initially, the sentient machines would be like their designers. Once the machines are allowed to develop organically for several generations, they should be able to find their own way of doing things. For instance, in Matrix we saw machines that were thoroughly alien, because they were designed by machines.
Many generations later, these machines might encounter machine descendants of another long lost biological empire. Would they be vastly different, or would they converge on the one obvious way of making sentient machines? Who knows. Galaxies and orbits tend to be disk shaped, because that’s the obvious stable configuration things gravitate towards. Maybe intelligence and sentience has to follow a similar force of nature, and therefore, convergences on just one successful configuration.