VIOS

VIOS (Virtual Icon Of Sin) is an AI of demonic origins and the main antagonist of Doom II RPG.

Tactical Analysis
VIOS is, as the name implies, a Virtual Icon of Sin. He interacts with the player through corrupted terminals. When accessing these terminals, the player can either allow VIOS to corrupt the terminal's data, or delete it. If the player chooses to delete it, VIOS fights the player. If the player wins the fight, the data is deleted. The fights get harder the further into the game you go, and deleting the data weakens VIOS for the final fight.

Final Fight
The final fight is set up as six terminal fights with VIOS, like the player has been doing throughout the game. Above each terminal is a portal that closes when the VIOS of that terminal is defeated. After defeating VIOS in any of the terminals, the player will be attacked by other demons. After the sixth VIOS is beaten, he is killed by a well-aimed rocket fired into his forehead.

Terminals
There are corrupted Mainframe Terminals in the following levels:
 * Cichus
 * UAC Administration
 * UAC Labs
 * Gehenna
 * VIOS (Level)

Trivia

 * During the player's first encounter with VIOS, if you interact with the terminal using a Sentry Bot, VIOS will say "A sentry bot. How quaint. Put it away."
 * Also during this encounter, VIOS flashes onscreen before several demons spawn.
 * The Holy Water Pistol and the Soul Cube are unusable in all VIOS fights.

Bugs

 * When you get VIOS' health to the point where he'd normally end the fight, the game can break causing him to skip his turns. If you kill him, he'll disappear and you'll be free to roam his little digital room.
 * In the level VIOS, if you manage to kill VIOS before going through the other 5 terminals (in a manner such as the above bug), it will go to the ending cutscene.