Graveyard

A graveyard is a series of gravestones that release a pack of skeletons during night time and can be found on the surface of the forest, the snow, and the desert worlds.

General characteristics
Each graveyard is a flat piece of land, which means their graves are always at the same terrain level.

Graveyards are all randomly generated when the world is created, that is right before the first dwarf's arrival.

Their random aspects are:
 * location (to the left or to the right, farther or closer to the shelter)
 * amount of gravestones (any number from three to six).

Gravestone


A gravestone is a type of 1x1 foreground stone block that spawns a random skeleton every night, and form the graveyard.

A destroyed gravestone drops one stone and won't spawn skeletons anymore. If destroyed over night, a skeleton will spawn and avenge his grave.

Wave composition
Every night graveyards may spawn the following types of skeletons:
 * Regular skeleton
 * Skeleton builder
 * Skeleton archer
 * Skeleton with shield.

Wave range
Once risen those skellies will head towards the dwarfs base, and try to reach it before surise. All, some or none of them will get there depending on:
 * how far the graveyard is from the shelter
 * the amount and height of natural obstacles between the graveyard and the shelter
 * the amount of melee skeletons spawned on a given night, that would create shield stairs to overcome those obstacles.