ancient civilization, downloadable content (DLC), expansion pack, new civilizations, unique units, cultural buildings, historical leaders, strategy game, turn-based, enhanced gameplay, additional scenarios, world wonders, special abilities, multiplayer maps, resource management, technology tree, diplomacy options, city-state allies, military tactics, trade routes, cultural influence, global domination, 4X game mechanics, empire building, historical events, mod support, high-resolution textures, improved AI, user interface upgrades, soundtrack, special promotions, limited edition, collector's items, game patches, online community, Steam workshop integration, cross-platform play.