The Japanese enter the fray on Luminith: their faction has a very strong military and a very strange pantheon: their gods are much more aggressive than their Greek and Norse counterparts, and each has three god creatures rather than three god tokens. Learning to play this new faction effectively is a fun new challenge: given how powerful the Japanese military and mythology are, you have to be very creative in how you help the Norse and Greeks drive back this threat. Remember, no faction is supposed to dominate the other!
Hamlets are new non-combative, non-factional villages that can be built in the remains of the fallen towns. But it's never that easy! Hamlet buildings can only be placed from a limited queue that cycles as you place them. Hamlet buildings generate (or lose) Culture depending on what pre-existing tiles were adjacent at the time you placed them. Culture allows you to activate four powerful new abilities, including creating Large Towns or even turning back time. Amass enough Culture and Sunstone and you can even win the game via a new Cultural Victory!