Exterminator is a mission on the game Mission: Von Nebula. It is available at any stage in the game.
When you enter the room the first thing you need to do is defeat the three bots in the room. Once that is done the next wave will start. In this wave there are three bots but this time there is a Shooter bot which you have never fought before. Once these are all beaten you progress to the next area.
In the next area you are met by three more normal bots. These must be defeated in order to progress to the next wave. In the next wave there are two normal bots and a shooter bot. once these are beaten the next wave will start. Now you will face four bots, two are normal while another two are shooter bots. You must then go to the next area. There you will face a boss bot. It is best to have a shooter when facing him but a fighter can win, but be careful. Once you have beaten it progress through the door. Well done, you have completed the mission.