Zbot is a different animal. It is a 'proxy'. It is a separate program loaded through a dos box which connects to the server and passes the information through to the Quake game. By intercepting the raw data from the server, it can determine the exact location of every other player in all three axis and use the info to override the player's input and aim for him. This can allow the proxy to immediately fire in any direction, just like you had eyes in back of your head. The proxy works from a menu or through key bindings, and can be activated or deactivated on the fly.  The players movement is not affected by Zbot except for turning to aim, after which the player snaps back to his original orientation. The FOV of the Zbot proxy is adjustable from 360 degrees down to a narrow field (5-10 degrees). By narrowing the FOV, the user can attempt to hide the workings of the bot. This is one of the main ways you will notice that a bot is in use. If the FOV  is set wide, the player will immediately fire on any enemy player that walks into range. The user may be two stories down, under water, facing the other way, and you peek out over a ledge that you just got to and you know he cant see you, and suddenly, before you can even look, bulls eye. You get rallied by the ol railgun. (The rail is the favorite weapon of the Zbot user). Then just as fast as the re-fire rate of the rail will allow, another shot is fired in the opposite direction and bulls eye again.