The Mothership is a bonus level that can be accessed from the alternative exit that always appears on The Ice Caves, in the fourth level. It appears in a futuristic structure that extends from the ceiling, with a door at the top of the structure.
It is a very volatile place - automated defenses and explosive enemies will tear the level apart to get at you, and the Alien Lord's psychic attacks will more than likely kill you immediately if you are hit.
Unlike other levels, this level goes in reverse. You will enter the level at the bottom of the map, and the exit will be at the top. When you exit, you will return to the beginning of 3-4 and be forced to do the level again before entering the Temple, meaning you will be forced to complete an extra two levels on a standard playthrough.
None of the tiles in the Mothership have items or treasure inside them, but the blue lights on ceilings can drop sapphires when broken.
The Robot Spelunker can be found inside a capsule there.
- The Shopkeeper will only appear if the player is wanted by them.