So I've got a small rather low tech start going. There is a jump gate in the Sol system. Turns out it leads to Banard's Star, where there is an NPR (and a jump gate back to Sol). They seem friendly, and I'm not going to mess with them being so low-tech still (I still haven't finished Jump Point Theory). They send some geo scouts into Sol, but nothing I want to do about it since I've seen ships twice the size of mine in their fleet.
Several months later, another set of ships appears through another WP (I still haven't surveyed Sol's jump points yet) and three of them head for Earth. I get my PDC and tiny fleet fired up and wait for them.
They never reach Earth because a task force from the first Banard Star aliens takes them out.
Several months later there is another battle between them in the Sol system, with the Banard Star guys again taking them out and me just watching from Earth orbit.
Pretty funny stuff, though I imagine the pop of Earth would be freaking out the whole time with this (too bad I wasn't writing this up). Looking in the database I see that there are four NPRs out there currently (I only specified 1 in the startup), 35 star systems besides Sol (I have only been to Banard's Star) and I am getting all sorts of slow time chunks due to fighting going on.