Civilization VI builds upon the general gameplay of Civilization V, including continuing the use of the hex-based grid introduced in Civilization V. New to Civilization VI is the of idea of “city unstacking”: some improvements to cities must be placed in the hexes in the bounds of the city but not within the city’s space itself, whereas in previous games, all improvements were considered stacked on the same map hex or square that the city was located in. The player must specify specific hexes as “districts” in the city, which have certain limitations but grant bonuses for improvements placed in that district. For example, one district type is of military encampments, which grants bonuses to military structures, like barracks, placed within it, but such encampments may not be placed next to the main city center. Other improvements gain bonuses for being placed in appropriate terrain; universities will benefit greatly from being played in forest or jungle hexes, reflecting on scientific advance from studying the diversity of species within such biomes. Players can opt to attack specific districts of a city instead of the city center, which can affect on the city’s operation. However, these districts may also add new strategies to the city’s defense; for example, with a military encampment in place, advances forces approaching a city will be not only subject to ranged attacks from the city center but also from the encampment, and the advancing forces may need to take the encampment first before they can successfully strike the city center.
In order to reduce congestion on the map, players will be able to perform a limited amount of unit stacking (a change from Civilization V), but will only be able to stack similar unit types or symbiotic units. For example, a warrior unit can be assigned to a worker unit to protect that unit from barbarians in the early game.
The game’s technology tree, now known as the active research system, has also been modified to help boost technology research if the player has access to appropriate improvements or resources. For example, having built a quarry will help boost the research into masonry. Technologies based on having access to water, such as sailing, would be limited if the player started in the middle of a continent. A new feature, Eureka Moments, will increase the player’s progress towards certain technologies after completing a specific in-game task: for example, discovering a Natural Wonder would contribute towards the Astrology technology improvement.