The G-Virus is an item distributed through the Zombie Defense Pack, as well as being obtainable from surgery. It is unspliceable and if a player gets punched by a zombie with the g-Virus, the player becomes a zombie. Direct infections with the g-Virus ignore the immunity granted by an Antidote and the Zombie Jammer.
- The item was added as a prize for the winner of the GROWTECHPHARMA world. The winner of the item was Viking, though unsuable at the time, was labelled "Mysterious Liquid". The GrowTech Pharma storyline suggests that the zombie virus began with the stolen virus.
- When an infected player chats, their message appears in dark green, with "Zombie speak" added on occasion, such as "BRAINS!" or "Brraaiinnss...". The zombie speak originally extended vowels and alternated capitalization randomly, but that was cut so chatting as a zombie would be less annoying to players.
- A Zombie Jammer can be placed in a world to prevent any player from infecting other players.
- Zombies are the main antagonist in the Zombie Pandemic event in which Zombie Jammers and Antidotes won't work.