Home News Sins of a Solar Empire: Diplomacy pre-orders open News by Patrick Garratt Founder & Publisher (Former) Published on Sept. 16, 2009 Stardock's opened pre-orders for Sins of a Solar Empire micro-expansion, Diplomacy. See here. The add-on will bring a new tech tree, new ships and "deadlier pirates" to the space-based RTS. Yours for $10. It's out February 9. Buy it here.