Test cells are locations included within a games files but are located outside the main world map. They are used by developers to test a variety of content, including (but not limited to) physics, dialogue, textures, and traps. In Fallout 3, there are 29 test cells containing content in the base game, with an additional 10 in Operation: Anchorage, 10 in The Pitt, 12 in Point Lookout, 2 in Broken Steel, and 17 in Mothership Zeta. Operation: Anchorage also contains a unique test worldspace, tLandscape, which contains and additional 9 conjoined test cells. This brings the total number of test cells for Fallout 3 and its add-ons to 89. There are also several empty test cells that exist the games files, but are completely empty.