star systems (each has four regular levels plus a secret level), for a total of 30 levels. The full base Descent II game was published for DOS by Interplay in March 13, 1996. It was co-distributed by LaserSoft Imaging, whom Interplay gave the rights as part of a settlement after the former lost a court battle regarding its product add-on for the first Descent game, which Interplay alleged infringed its trademark—setting a precedent for how companies can sell add-ons for protected games. Interplay's division specified in Macintosh games, MacPlay, published it for Macintosh in August 1996. Descent II: Destination Quartzon was a truncated version with the first eight regular levels and two secret levels (constituting the first and second star systems, "Zeta Aquilae" and "Quartzon"). Not compatible with the Descent II full release, Destination Quartzon was bundled software with hardware such as the Logitech WingMan Extreme joystick and Diamond Multimedia video cards with the Voodoo Graphics chipset. In November 1996 came Descent II: The Infinite Abyss, a Windows 95 upgrade that supports 3D accelerated graphics, contains The Vertigo Series add-on, and the original DOS game patched to support accelerated graphics. The Vertigo Series, which could be purchased separately, contains 22 new levels (to be played sequentially), a new multiplayer game mode, new music and enemies. The add-on is also bundled with the Mission Builder, a level and robot editor that can also convert the original Descents levels for this game. In March 1997 in North America and mid-1997 in Europe, the PlayStation version of Descent II, known as Descent Maximum was launched. Instead of a straight port, it had 36 new levels, textures and full-motion video over the PC version of Descent II. On October 29, 1997, Interplay published Descent I and II: The Definitive Collection, a compilation containing the full versions of Descent, the Levels of the World mission pack, Descent II, and Vertigo mission packs, and a mission editor. Besides a choice of the original Descent II levels (subtitled Counterstrike), or the Vertigo Series levels, the first Descent levels (subtitled The First Strike) can be started in the Descent II game UI where robots adopt the Descent II sounds and improved AI. There is also a preview for the upcoming Descent 3. In 1998, the Descent II source code, like that of Descent before it, was released to the general public under a copyrighted proprietary license, leading to