In a multiplayer game, the other players appear as space marines in differently colored space suits. In [[vanilla Doom]], the colors are green, indigo, brown and red. [[Source port]]s typically permit more choices of color, and sometimes more than four players. The [[sprite]]s for a player are rendered in a green suit; to draw another player, the [[Doom rendering engine|rendering engine]] remaps the shades of green to shades of the desired color.
A player spawns with 100% health, a [[pistol]], and 50
[[bullet]]s. The [[fist]]s may also be used as a weapon. When respawning in vanilla Doom, everything else ([[armor]], other weapons, [[ammo]], [[powerup]]s, and [[keys]]) is lost. In [[deathmatch]] mode, an exception is made to this as players spawn with all keys. Some source ports permit respawning to other states.
In order to be playable in single player mode, a level must have a "Player 1 start" [[Thing]]. Player starts 2 through 4, typically located close by, enable [[cooperative]] play. [[Deathmatch start]] positions are usually located far from each other; one is chosen at random each time a player spawns.