Quake II is a first-person shooter, in which the player shoots enemies from the perspective of the main character. The gameplay is very similar to that featured in Quake, in terms of movement and controls, although the player's movement speed has been slowed down, and the player now has the ability to crouch. The game retains four of the eight weapons from Quake (the Shotgun, Super Shotgun, Grenade Launcher, and Rocket Launcher), although they have been redesigned visually and made to function in slightly different ways. The remainder of Quake's eight weapons (the Axe, Nailgun, Super Nailgun, and Thunderbolt) are not present in Quake II. The six newly introduced weapons are the Blaster, Machine Gun, Chain Gun, Hyperblaster, Railgun, and BFG10K. The Quad Damage power up from Quake is present in Quake II, and new power-ups include the Ammo Pack, Invulnerability, Bandolier, Enviro-Suit, Rebreather, and Silencer.

Quake II Mission Pack: The Reckoning
Quake II Mission Pack: The Reckoning is the first official expansion pack, released on May 31, 1998. It was developed by Xatrix Entertainment. It features eighteen new single player levels, six new deathmatch levels, three new weapons (the Ion Ripper, Phalanx Particle Cannon, and Trap), a new power-up, two new enemies, seven modified versions of existing enemies, and five new 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. Notably, 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.

Quake II Mission Pack: Ground Zero
Quake II Mission Pack: Ground Zero is the second official expansion pack, released on September 11, 1998. It was developed by Rogue Entertainment. It comes with fourteen new single-player levels, ten new multiplayer maps, five additional music tracks, five new enemies, seven new power-ups, and five new weapons. In the expansion's story the Gravity Well has trapped the Earth Fleet in orbit above the planet Stroggos. One of the marines who managed to land, Stepchild, must now make his way to the Gravity Well to destroy it and free the fleet above and disable the entire defenses of the planet.

Quake II Netpack I: Extremities
Quake II Netpack I: Extremities contains, among other features, 11 game mods and 12 deathmatch maps.