Quake II Mission Pack: The Reckoning is the first expansion pack, released on May 27, 1998. It was developed by Xatrix Entertainment. First announced in January 1998, it features eighteen single player levels, six deathmatch levels, three weapons (the Ion Ripper, Phalanx Particle Cannon, and Trap), a power-up, two enemies, seven modified versions of existing enemies, and five music tracks. The storyline follows Joker, a member of an elite squad of marines on a mission to infiltrate a Strogg base on one of Stroggos' moons and destroy the Strogg fleet, which is preparing to attack. Joker crash lands in the swamps outside of the compound where his squad is waiting. He travels through the swamps and bypasses the compounds outer defenses and enters through the main gate, finding his squad just in time to watch them get executed by Strogg forces. Next, Joker escapes on his own to the fuel refinery where he helps the Air Force destroy all fuel production, then infiltrates the Strogg spaceport, boards a cargo ship and reaches the Moon Base, destroying it and the Strogg fleet. The section of the game that takes place on the Moon Base has low gravity, something that was previously used on one secret level of the original Quake.