The krepost in Civilization V is one of the most simple, elegant, nearly hidden pieces of design you are likely to find. Every Civ V civilization gets a special ability and two altered units or buildings. The Roman legions can build roads, the Siamese wat combines culture and science, and the Americans are good at bombing things. The Russian unique building is the krepost, which replaces the barracks. It is a normal barracks plus a 25% reduction in the culture cost to acquire new tiles. Like the barracks, it is unlocked with Bronze Working, an Ancient Era technology.
That one bonus on one building creates a dynamic that simulates Russia beautifully. It encourages you to build a barracks in every city, even for a quasi-pacifist player like me who has no need to build troops in every city. That leads naturally to a more militaristic playstyle. The bonus also facilitates the creation of a large empire with extensive borders. Those borders will put you into conflict with neighbors who object to your taking up half a continent, but those neighbors might be hesitant to mess with an enemy who is prepared to mobilize troops in every part of the empire. And this mechanic starts in the earliest stages of the game, which gives it time to define your strategy and to let those cultural borders expand.
Add one unrelated bonus to one item and watch the entire play dynamic change.