Experience points (XP) represent a character's growing abilities, gained from performing various in-game activities. When sufficient XP have been amassed, they can be exchanged for new skills. Neither survivors nor zombies can lose XP. (Prior to December 19, 2005, the Headshot skill could reduce XP when used against zombies.)
When humans die, any XP that they had transfers over when they become zombies. Zombies that are revived also keep any XP gained as a zombie for use in their human form.
Activities that earn XP
- Combat (fighting them) - XP gained is equal to damage dealt for human-zombie combat. A bonus of 10 XP is granted when you kill your targets by reducing them to 0 HP. Combat is the main method of XP gain available to zombies.
- Combat (fighting your own) - Human-human or zombie-zombie combat earns half the normal rate described above (rounded down for odd amounts of damage).
- First Aid - a player who uses a first-aid kit on another player gains 5 XP (the First Aid and Surgery skills, which increases the amount healed, do not change the XP gained). Players healing themselves do not earn XP. Curing infection does not give XP. Healing zombies DOES provide XP.
- DNA Extraction - players with the NecroTech Employment skill can use DNA extractors to send data on a zombie back to the NecroTech corporation for 4 XP. Each zombie can be "tagged" only once in calendar day (by UK time). Repeated attempts on zombies in a stack move down the stack with each attempt.
- Revivification - a player with the Lab Experience skill who uses a revivification syringe to successfully revive a zombie gains 10 XP.
- Tagging - a player with the Tagging skill and a spray can can gain 2 XP for putting graffiti on Armories, Monuments and Police Departments and 1 XP for putting graffiti on Banks, Mansions, Power Stations and Schools.
- Dumping bodies - Dumping a body outside a building earns 1 XP per body, but bodies must be removed individually.
- Repairing Buildings - repairing a building that has been Ransacked will give 1 XP.
- Repairing Equipments - repairing a generator or a radio that has been damaged will give 1 XP.
- Reading - reading a book has a 10% chance of giving 1 XP through studying (2 XP for Scientist class players).
- Destroying Barricades (zombies) - Removing a barricade level from a building will give zombies 1 point of XP per level removed. Survivors get no experience for removing barricades.
- Ransacking Buildings (zombies) - Ransacking a building will give zombies 1 XP.
- Equipment Destruction (zombies) - Destroying a generator or radio transmitter will give zombies 5 XP.
- Decoration Destruction (zombies) - When a building is ransacked, zombies can destroy a single decoration for 1AP and 1XP. Only one item is destroyed at a time, and survivors cannot destroy the decorations.
Activities that don't earn XP
- Barricade - Barricading a building grants no XP, but does make for a safe place to sleep for the night, and offers a chance for zombies to earn XP by smashing them.
- Installing a generator - Hooking up a generator grants no XP, but offers a chance for zombies to earn XP by smashing it.
- Refueling the generator - Filling a generator with fuel grants no XP, but makes fighting easier for survivors, which in turn grants various amounts of XP.
- Ruin (zombies) - Ruining a building grants no XP.
- Attack the barricades (survivors) - Attacking barricades grants no XP for survivors.
- Attack the generator/transmitter (survivors) - Attacking radios and generators grants no XP for survivors.
- Placing decorations - Placing a museum piece or holiday decoration inside a building does not grant XP for survivors, though it allows zombies an oppurtunity to gain XP if they are able to destroy them.
- Defiling graffiti/cleaning graffiti - Using the defile graffiti action as a zombie or cleaning defiled graffiti as a survivor does not grant XP.
- Speech/Radio transmission - Speaking, whether as a survivor or as a zombie, or broadcasting over a radio transmitter will not grant XP.
- Feeding groan/bellow - Zombies using the groan or bellow actions are not granted XP.
- Setting/scouting safehouse - Setting a safehouse with the set safehouse action or using the Scout Safehouse skill does not grant XP.
- Scent Death - The zombie skill Scent Death does not grant XP.
- Gesturing - Zombies gesturing at players or objects do not earn XP.
- Corpse Feeding - Feeding on a dead body as a zombie does not grant XP.
- Failed actions - Any action that fails, such as missed combat actions, failed revivification, healing a player already at full health or DNA scanning previously scanned zombies does not earn a player XP.