Valve's Steam service just got infused with some additional Sid Meier goodness. A new update to Steam reports that Civilization IV: Warlords and CivCity: Rome are now up for sale on the digital distribution service.

Here's the original announcement from Steam:

Two new products in the legendary Civilization series are now available for purchase via Steam, Sid Meier's Civilization IV: Warlords and CivCity: Rome. Sid Meier's Civilization IV: Warlords, available for US$ 29.95, is the first expansion pack for the award-winning Civilization IV and delivers new scenarios, civilizations, leaders, and units. CivCity: Rome, available for US$ 39.95, is a city building strategy game inspired by the world of Sid Meier's Civilization.