There are many controversial opinions on every CIV game. But a CIV game where a single barbarian captures your second biggest city with a rank 2 unit defending unit, only for the city to be captured by an AI player in the same turn is just infuryating and this happened on the chieftain difficulty. The religion mechanic is just another irritating waste of time. Having to choose a tech more often than you choose what to build. "Governments" that you can fully skip, without loosing on anything. I hate this CIV game. You can skip it, go from 3 directly to 5.