When Bobby Kotick had control over Hell, Activision had monopolized the video game industry in that world; it is unknown what happened to it once Smoosh defeated him. Activision's headquaters is portrayed as being a castle in the Ninth Level of Hell; it was the site of fourth boss battle.
As seen in Luna's flashback, Activision existed sometime before Kotick's transformation into Satan. In the flashback, Kotick says he doesn't want the Royal Family of Luna's homeworld to die, or else "Activision is going to lose a lot of stock." This opens up a possible plot hole, however; Hades told Smoosh that Bobby Kotick became Satan around 2000 years ago (a reference to the creation of Christianity), while Luna is a very young woman.
Sometime later, Bobby Kotick managed to steal away Hades' title as master of the Underworld, and he became Satan. Activision became very strong and rich with the aid of Bobby Kotick's evil power.
It is unknown what the company's fate was after Kotick's removal from his position as Satan, or if it even still exists at all.