The game starts when you first enter the main control module of Cray-5.
Once there, you should disconnect the host, and go to the escape pod to return to the main hall.
For safety reasons, the Cray-5 control module is separated from the rest of the ship, cannot be accessed from it, and, moreover, is segmented into 9 watertight levels.
To disconnect the host computer, you should turn off each and every one of the switches scattered in nine zones. In each area you will find a teleporter that may carry you to a variable number of other areas, depending on how many switches you have turned off.