The FTL developers, Subset Games, are working on a single player turn-based-strategy game that looks a bit like Advance Wars. Into The Breach has no release date yet, but it will be out (not simultaneously) on Windows, Mac, and Linux. Here’s their description:
The remnants of human civilization are threatened by gigantic creatures breeding beneath the earth. You must control powerful mechs from the future to hold off this alien threat. Each attempt to save the world presents a new randomly generated challenge in this turn-based strategy game.
I’m pretty disappointed that Nintendo hasn’t announced a new Advance Wars, but I’m willing to bet that Subset has a good spin on it.