PlanetSide is the world's first major Massively Multiplayer Online First Person Shooter, which means that unlike other First Person Shooters (such as the Quake series, Unreal series, Halflife, Counterstrike, Medal of Honor), battles in Planetside make a difference. Three factions -- The Terran Republic, The New Conglomerate and The Vanu Sovereignty -- vie for control of a single world encompassing several continents. Territory must be captured and held for factions to advance, and individual combatants have the ability to influence the planetary power struggle.

Though not to be confused with a Massively Multiplayer Online Roleplaying Game such as EverQuest, Ultima Online, Dark Age of Camelot and Star Wars: Galaxies, PlanetSide does contain RPG elements. Players earn certifications that allow their characters to specialize, fulfilling different crucial combat roles. Characters can be vehicle specialists, giving them the ability to fly combat aircraft, as well drive troop transports, futuristic tanks and other vehicles into battle. Other players may choose to play as medics, shock troops, infiltration experts, etc. Although players are allotted a certain number of basic certifications when they begin playing PlanetSide, further certifications must be won on the battlefield similarly to how RPG’s award characters experience points for successful fights and quests.

Combat in PlanetSide will be familiar to anyone who has every played a First Person Shooter -- featuring real time “twitch-based” action -- though the game again borrows from RPGs by allowing players to have an inventory. However, unlike RPGs, players can spawn any items they’re certified to use at special stations for free, with the only limitations being how many items they can hold in their inventory. Ammunition is limited, so players who run out of ammo must either get more from another player, or run back to base to re-supply themselves.

PlanetSide is currently under development at Sony Online Entertainment (formerly Verant Interactive), the creator of EverQuest and the forthcoming MMORPG Star Wars: Galaxies and is slated for an early 2003 release.