Besides having changing civs, the most controversial and interesting change in Civ7 is the Ages mechanic. Instead of playing one game, there will be breaking points after roughly 150-200 turns, where you switch your civ, and many other things also happen at the same time. This includes that in each age there will be different mechanics present, some resources will only be available in certain ages, buildings will get obsolete, religions become available, and many more. If you are interested in a good overview, check the thread made by our user thecrazyscott, who has put everything together for you to read. Check it here, and let us know what you think.