DUO (Dimensional Unibody Offender) is the main antagonist of Varth: Operation Thunderstorm. DUO is a malevolent consciousness, which invaded and took control over the super-computer Delta-7.
In the colony planet Varth, all machinery was controlled by Delta-7, to the point that Varth's people simply let Delta-7 do everything for them. DUO decided to get rid of the humans, so with all machines under it's control it manipulated Delta-7 into forcing the humans into a war, which decimated 80% of Varth's population. That was not the end, however, as DUO sends all machines to exterminate the remaining humans. With little means of fighting back due to their overreliance on the super-computer, the remaining humans last hope was two planes equipped with 4th generation computers, which DUO could not take control due to them being human-operated. With two pilots chosen to pilot the planes, thus started the "Operation Thunderstorm".
The two planes fight against DUO's forces and invade the Delta-7 base, destroying the super-computer along with DUO. The ensuing explosion vaporized everything within a 50 mile radius, leaving a huge crater behind. The two pilots barely managed to escape the explosion.