Null Terrain

All tilesets in StarCraft contain "null terrain" -- solid black tiles with strange properties. However, only third-party map editors (that allow access to all tiles in a tileset) allow mapmakers to place such terrain.

Most null tiles are buildable but not walkable. Some of them, however, have different properties. They tend to share the same basic properties (such as doodad placement and buildability) as the rest of their containing rows. Mini-tile-specific properties (such as vision height, ground height, and unit walkability) are not shared.

Walkable Null Tiles

The null tiles that are found in the tileset index to the right of the creep tiles are walkable in all tilesets except for Installation.

Ground units cannot walk from normal terrain onto walkable null terrain. They must be moved or created on it with triggers, dropped onto it from a transport unit (such as a Dropship), or Recalled onto it with an Arbiter. Ground units can walk from walkable null terrain onto any other tiles, even if those tiles aren't walkable. (For example, units can walk from null to water.)

Buildable Installation Tile

There are no creep tiles in the Installation tileset. Because of this, the walkable null tiles that work in the other tilesets (essentially, a null version of creep) are not walkable in Installation. However, Installation does have another type of special tile: a buildable Substructure tile.

If a Zerg building is created on this terrain, "null creep" (a creep version of null) will grow. This creep does not function normally. Ground units don't move over it easily.

Black creep in Installation: