Zombie 1: Original

Zombie Mode is a mode official in Counter-Strike Online, done by NEXON Corporation, with the help from Valve Corporation. It is based on a custom mode from Counter-Strike. There are many improvements since the original mode, making it one of the most played mode in Counter-Strike Online.

Gameplay
Zombie Mode is round-based gameplay, same as much as the other modes. After 20 seconds before a round, one or two or more of the players are chosen to become a host zombie (This depends on the number of the players in the round). The host zombie must affect all of the humans by hurting them with melee attacks. Hurting humans will turn them into regular zombie and the regular zombie must attack other humans. The zombie team is counted to be win the round after all of the humans have been infected. On the other hands, the humans must either kill all zombies or survive the round unscathed in order to win.

Human
There are several modifications for humans in this mode:
 * Ammunition have been powered up. The player can hold up more bullets in a round.
 * In the next round, the weapon is reset and the player must buy new weapons.
 * The maximum health point limit for human is boosted to 1,000.
 * The human can only wear Kevlar vest instead of Helmet.

Zombie

 * Zombies can only affect humans with melee attacks.
 * Zombies have greater health points, movement speed and jumping height.
 * It takes greater damage from shotgun and sniper rifle shots, melee attacks and explosive grenades.