Civilization 7 is "one of the biggest changes" and also "one of the scariest" in the 34-year history of the strategy series

gamesradar.com:

Civilization 7 is looking to change up the tried and true formula of previous entries with a new core mechanic, and it's a big deal. 

The new Ages system breaks each match into three distinct parts, giving players freedom to change up their leaders and Civilizations at different points throughout a match. This new mechanic is “one of the biggest changes we've made to the game and one of the scariest in terms of changing Civilization, something that's so consistent," executive producer Dennis Shirk tells Techradar. This system will fundamentally shift the ebb and flow of each match, allowing players to catch up or change their strategy with the coming of each new Age.

However, while it might be scary to chart new waters in a long-running series, Shirk looks at it as "a new puzzle to unlock" and for players to discover themselves. The three Ages give everyone a chance to feel that sense of discovery multiple times throughout a match instead of just in the first 100 turns or so. Shirk goes on to explain a bit more how Ages will push player progression and discovery: "In the first Age you can't cross the oceans, but you're exploring your continent. Then the Second Age opens up. You get to another advanced level of shipbuilding, for example, and now you can traverse the oceans." 

Whether you're in the Age of Antiquity, Exploration, or the Modern Age, you'll have the option to change your civilization and leader to take advantage of your newly discovered surroundings or to avoid the impending doom threatened by another player on the map. Mixing and matching the strengths and weaknesses of a civilization and leader can create some unique combinations unseen in the series before. Shirks mentions "each leader has an attribute tree that is unique to them," allowing for players to better tailor a specific leader to their playstyle.  

The new Ages system seems like it's going to be a massive shake up for the franchise, and Shirk says it was crafted "with care and with time and