Acre
Acres are grid elements measuring 16x16 spaces and can be thought of as a basic unit of the player's town map. Each game in the Animal Crossing series arranges these preconstructed acres in novel ways to generate thousands of different possible town layouts. In all games prior to and including Template:AFe+ there was an explicitly designated acre system viewable from the map screen. Subsequent titles removed the explicit acre system in favor of an open and scrolling rounded-world design, although the acres are still used to determine perfect town status (Animal Crossing: New Leaf being the exception).
In Animal Crossing: amiibo Festival, Template:AF+, Animal Crossing and Template:AFe+
These games feature the largest town map in the Animal Crossing series measuring six acres across by five down. Town maps are generated semi-randomly; some acre models may only appear in a designated space (the Train Station is always located in Acre A-3) while others are more flexible.
In a new town, the only time two trees will be diagonally adjacent is when they are in adjacent acres. Each day, a beehive will spawn in five random oak or cedar trees and two other random oak or cedar trees will spawn a furniture item. Note that if a certain tree minimum is not met all the beehives and furniture items will not spawn. Tree count minimums also apply when trying to achieve a perfect town rating.
Every time the player moves into an acre (with the exception of exiting your house upon loading the game), one fish and one bug spawn at the locations programmed within the acre data. The bug and fish within the acre disappear upon moving six squares away from that acre. Bugs cannot move outside of an acre; should a banded dragonfly fly outside of the acre it will fly up and disappear. However, fish can move with the river current and end up in the next acre. The bug and fish that appear in the acre is determined by its rarity.
In Animal Crossing: Wild World
Acres don't exist in Wild World, instead the game uses the terrain models that are identical to that of what is used in an acre from the previous games, but they can be considered 'acres' since the terrain models are placed randomly upon beginning your new town in the same way as acres are determined in Animal Crossing: amiibo Festival, Template:AF+, Animal Crossing and Template:AFe+. There is 16 terrain models placed randomly in the town upon starting your new town (opposed to Animal Crossing's 30 and City Folk's 25), but each terrain model is still 16x16 in perimeter, just like the acres in earlier games. That means each terrain model is 256 squares in total area and that also means the entire town is 4096 squares. In Wild World, there is a 8/20 chance that a regular tree gives out 100 bells daily, when shaken. Additionally, in Wild World, there is also a 3/20 chance of encountering a swarm of bees when an ordinary tree is shaken (3 swarms spawn daily, not to be confused with a honeybee), and 1 regular tree also holds some common furniture, which falls out when the tree is shaken. Additionally, cliffs have been removed from Wild World.
In Wild World, fish and bugs no longer spawn upon entering the 'terrain model' (or what was called an acre in previous games), instead the game uses the spawn spots within the terrain model which will or will not spawn a fish or bug. The bugs and fish always spawn in the spawn spots out of viewing range of the camera. Like in the previous games, it uses two separate percentage roulettes out of 100% (200% in total) for a bug and for fish to determine which bug and fish spawn in the spawn spots. But unlike the previous games, some percentage can be nothing at all, some percentage can be common bugs or fish, some uncommon bugs and fish and while a few percentage can be rare bugs and fish, where as the previous games always spawned one bug and one fish upon entering an 'acre'.
Unlike the previous games, Wild World has a cylinder-like mapping structure, curved terrain models and continuous scrolling and does not use an acre system or even display acre boundaries on the map. By looking closely at the river, there will be a slight break in the waves when they cross the edge of a terrain model. In addition, no rock or building will be placed on the outermost square of a terrain model.
In Animal Crossing: City Folk
The terrain models are very similar to the terrain models in Wild World and the acres in the N64 and GCN Animal Crossing games, and function in much the same way as Wild World. As in Wild World, it uses a cylinder-like mapping structure, which means the terrain models are curved in City Folk as well. There are still 16x16 squares, as it was in previous games, but there are only 25 acres, unlike both its predecessors. City Folk has two separate cylinder-like maps, which is the town and the city.
The ratio of beehives, furniture and bells per acre is identical to Animal Crossing. Like Wild World, City Folk has continuous scrolling and does not use an acre system or display acre boundaries on the map. Just as in Wild World, by looking closely at the river, there will be a slight crack in the river banks when they cross the terrain model edge.
City Folk uses the very same percentage roulette system for bugs and fish in spawn spots as it was in Wild World, however fish now spawn in the spawn spots in viewing range of the camera as well as out of viewing range, but bugs remain the same in regards to spawning outside of viewing range.
In Animal Crossing: New Leaf
New Leaf has cliffs separating the town from the beach. Due to the improved processing power and expanded cartridge memory of the Nintendo 3DS, the map is bigger. New Leaf retains the cylinder-like mapping structure from it's previous two predecessors. It also has eight separate cylinder-like maps, which is the town, the ocean to Tortimer Island, Tortimer Island, the Main Street and the four parts of the Happy Home Showcase. Compared to City Folk where it only had two cylinder-like maps.
Villager's homes, town projects, buildings and player's own house can be built anywhere as long as it's two spaces away from the river (except if it's a bridge), the building, the cliff wall, the plaza or near the train track fence. It doesn't even have to matter if it's between two terrain models in the town. Unlike in City Folk and it's predecessors where it used signposts to indicate villager's home to be build on, New Leaf no longer uses signposts for villager's houses, as they are built anywhere around town where there is the least amount of trees.
Bug and fish spawn spots remain the same as they did in City Folk, with the same style of spawning.
