The plot of Dr. Betruger officially operates as soon as you and other essential characters arrive on Mars, starting the events in Doom 3.
Aboard the Darkstar, which landed on Mars on November 15, 145, in addition to UAC senior member Elliot Swann, there was an anonymous Space Marine soldier at the rank of Corporal called to the team. Instead of another soldier who died on a mission, and this is our main character.
The first task he was assigned was to search for a scientist named Jonathan Ishii, who had just disappeared, while Swann and Dr. Malcolm Betruger quarreled about what was happening on UAC’s Mars base. Blinded by the new dimension presented in front of his eyes, Dr. Betruger ignored all the advice and declared that great things would soon happen through his discovery.
Meanwhile, your attempt to reunite with your Marine soldiers is ultimately unsuccessful when all the survivors have been killed or controlled, with only a few survivors remaining as refugees relatively safe points. Sergeant Kelly had hoped for the Bravo group to be destroyed by a pack of Imp. Only one survived by pretending to die. This soldier gives you Swann and Campbell’s help message before being killed by a Wraith.
Even in this situation, Betruger still kept his confusing confidence when he told Swann that “everything is still under control.” This made Swann suspect that Betruger had some role in the invasion of Hell, and so he decided to join the bodyguard with Jack Campbell to open the bloody path to the Base’s Information Center to warn against any who goes down the red planet.
Meanwhile, your attempt to reunite with your Marine soldiers is completely unsuccessful when all the survivors have been killed or controlled, with only a few survivors remaining as refugees relatively safe points. Sergeant Kelly had hoped for the Bravo group to be destroyed by a pack of Imp. Only one survived by pretending to die. This soldier gives you Swann and Campbell’s help message before being killed by a Wraith.
When you came to the Information Center, Campbell destroyed its main control panel with his BFG9000. So Sergeant Kelly orders you to look to another location to send information for help. Here, you will have to choose between obeying Sergeant Kelly and Swann’s request when he wants you to hide the incident because he wants to keep the Mars base in the hands of UAC instead of letting the military take over. Whether you send a message or not, you’ll still have to go to Delta Labs to stop the demons from coming out of the gate that connects Mars to Hell, and you’ll meet Betruger on this new journey. Betruger reveals to you that he is the demons commander and has proactively informed the Earth fleet about taking the spacecraft and attacking the Earth.
At Delta Labs, our protagonist meets Ian McCormick, a researcher who will explain UAC’s projects on Mars, telling him that Betruger has brought the Soul Cube artifact to hell. That may be the key to stopping the invasion. McCormick also helps you teleport to the research labs of Delta Labs, where the gates of hell are still erupting evil. He defeated the two Hell Knights used by Betruger to block his path and enter Hell.
After defeating several demon legions in Hell, you find the Soul Cube and obtain it by destroying the Guardian of Hell, whom Betruger assigned to protect the antiquity. He brought the Soul Cube to Mars but was told by Betruger himself that he had another portal that could release millions of demons into the human universe. He also met Swann, who was seriously injured and was told that Sergeant Kelly had turned into an accomplice with Betruger, and Campbell was hunting Kelly. Swann also revealed that demons once appeared on Earth, but their presence has been forgotten over time.
To help Campbell, you’ll cross Delta Sector 1 of Delta Labs, which has changed a lot from what he saw just hours ago. He found Campbell was also seriously injured after fighting Kelly, and Campbell died after telling you that Kelly took the BFG9000 gun. You will avenge Campbell for killing Kelly – now Sabaoth – to retrieve the BFG9000.
After defeating Kelly, you come to Site 3, the excavation site that UAC found Soul Cube. Here, you meet archaeologist Pierce Rogers, and he said that the ancient Martians used both science and religion to create space gates connecting the Solar System planets, including the Left. However, the demons used these gates to invade the real world, forcing the civilization of Mars to create the Soul Cube and then use their souls to activate it, sending the demons to Hell. Some surviving Martians left the planet to fly to Earth, and modern humans are likely descendants of ancient Martians.
More than 24 hours after setting foot on Mars, you come to Caverns 1, the area where the current Mars base originated. Here, you find an elevator that goes deep into the ground, resulting in an ancient structure that has been damaged after countless years of being buried under the surface of Mars. Our main character will find more information about the Soul Cube and uncover a part of Hell that merged with Mars. Here, you will defeat a terrible Cyberdemon before using the Soul Cube to seal the gates of hell that Betruger once mentioned in this place.
Four days later, on November 20, 145, Earth’s Recon Zulu reconnaissance team set foot on Mars’s surface to occupy the area. They discover you are the only survivor on the entire base, and Swann died from his wound. Meanwhile, Dr. Betruger seems to have disappeared from the world because no one could find any trace of him.
Indeed, Dr. Betruger has disappeared from the world because he is now Maledict, a devil in hell.