Age Transitions Feel Like Starting a New Game
The most significant change compared to previous titles is the completely new approach to the game's ages. In most previous games, ages were called “era” (such as Ancient, Classic, Medieval, Renaissance, Industrial, or Modern) and were just signs to show how far you'd come in the tech tree. Sometimes certain buildings were locked behind eras, but they weren't actually a system in themselves.
Civilization VI He introduced ages as a complementary concept to eras. There was a sort of boom and bust cycle of golden and dark times, where you tried to achieve one or the other in the next cycle to get certain bonuses.
Confusingly, the ages in VII they mostly resemble past game eras and include some of the ideas from VIthe ages, while also totally reviewing the whole concept.
Now there are only three ages: Antiquity, Exploration and Modern. Each has its own completely different tech tree, and each has game systems that are completely relevant to that time and that time only.
Each era also has its own paths and metrics of success, similar to classic victory conditions. Yes, there are scientific victories for Antiquity, Exploration, and Early Modern, but the specific objectives of the scientific victory vary between them.
When an era concludes, it feels like the end of a classic Civilization game. A summary screen shows how different civilizations fared in their goals for the time, with rankings making it clear who (if anyone) came out on top.
When you start the next era, it's like starting a completely new game, except that the city location and other starting conditions are defined by the conditions you met in the game you played before. (I'm told this is similar to how Civilization-like Humanity works, but I haven't played that game, so I can't give more details).
This is by far the most radical change we've ever seen in Civilization's gameplay. Although I like it a lot. It's hard to explain why it feels so much better, but I think it's because it provides more frequent and meaningful rewards for the way you've been playing. It allows game designers to delve deeper into systems when they don't necessarily have to work the same way throughout the game.