There is a theory missing from this thread.
People have already suggested showing Dwarf Fortress to our new alien buddies/enemies, what makes you think such an advanced race doesnt have its own, better version of it?
of course it wouldnt be DWARVES, it would be their own mythological creature, and the simulated world would be much more complex... say simulating a whole planet in 3D with entire ecosystems and realistic physics. Hell I bet the AI involved would even be self aware, though it would likely not KNOW it was in a virtual world, if the aliens had a sense of humour they might even give the AI a crude ACII version of the similuated world to play about with just for the reccursion lols.
Now of course, if that AI ever became aware that it was simply lines of code as part of a large simulated world it would probably go insane... wait a second...
-Disgruntled Peasant is having a strange mood-
If it wasn't Dwarves, then it wouldn't be a far more advanced and better version >
Unless of course: the 'aliens' in question ARE dwarves!
us humans made dwarves the central characters, because we wanted to play as something we arent. dwaves think much the same, they want to see what its like to control a human culture. (it would also explain the absence of elves in our world, since no dwarf would ever want to even simulate such a stinking and vile creature)
In the REAL world, humans are the mythological creatures, and dwarves are a hyperadvanced society that has simulated its mythology in a digital world.