Diplomacy is Not an Option is described as 'An RTS game where hordes of thousands of enemies attack your castle and surrounding village. You must build walls and armies to defend against them by harvesting local resources and expanding your territory'. There are six games similar to Diplomacy is Not an Option for a variety of platforms, including Windows, Steam, Linux, Mac and Playstation. The best alternative is They Are Billions. It's not free, so if you're looking for a free alternative, you could try Second Earth or Védelem: The Golden Horde. Other Diplomacy is Not an Option like games are Age of Darkness (Paid), Conan Unconquered (Paid) and Alien Marauder (Paid).
Age of Darkness: Final Stand is a dark fantasy survival RTS where you must illuminate, build and defend humanity’s last bastion against hordes of Nightmares. Set in the remnants of a kingdom consumed by a deadly fog, you decide. Will you hide in the light? Represent entire series of Age of Darkness games.
“Alien Marauder” is a real-time strategy game with survival and confrontation theme. In this game, you will be the leader to a treacherous alien planet, build and defend base to survive against the vaxan waves. Make the right decision!