We don't use any middleware. The network layer is .NET-based TCP sockets coded by yours truly. I was originally using a network package for C# that I forget the name of now, but due to some threadlocking problems I decided to go with the current approach, which is event-driven rather than looping. That has other ancillary benefits, too.
Next for us is a puzzle game called Feedback, to hopefully be out late this year (we have not released many details on it yet, it is just passing the prototype phase basically), and then the first expansion for AI War around that same time period. The full list of planned stuff is on the right-hand sidebar of the main site, there are other games planned or in progress, but we're a small team and there's a lot of stuff going into improving the base game of AI War and adding free DLC, etc, so that may affect our schedule some.
I don't see the team for Arcen growing much anytime soon, but you never know -- I did not expect to bring on a techwriter/forum moderator, but it was totally worth it. None of us are fulltime staff members of Arcen at this stage, it's a part time thing for everyone. AI War is finally getting more press and getting noticed, and sales have been steadily rising for a few months now, but it's still not at the stage where anyone can quit the day job. There are a few exciting things in the works that will hopefully change that by year's end, though.
The company does not really have a physical location, per se. I was a big fan of virtual offices even before I founded Arcen, so I don't expect to ever have office space. Myself and the composer are located near Raleigh, NC in the US, and the game designer for feedback is in Seattle. Then our artist is up in Canada, and the techwriter is in the UK. So we're pretty much all over the place!