There are many AI units to be encountered around the map; they can be hostile or friendly. AI units have unlimited ammunition (as of 0.1.34). They typically have one weapon, a small amount of ammunition, an equipment item (compass, watch, etc), general items (documents, notebooks, etc), food, and water. They may also have a backpack or a vest.
Enemy AI[]
Bandits travel in groups of up to four or five. There may be several groups in an area at any one time. They will open fire on the player when they spot them. Bandits will also fight zombies and be attacked by them. A common way of detecting their presence is hearing them shooting at zombies.
Those must be friendly bullets they're firing at me
"Renegade" units function the same as other human infantry but resemble humans undergoing some stage of infection. Like humans, zombies will attack them and the player can loot their corpses. It should be of note, however, that if renegades die from zombies, they will come back to life as zombies. They are easily identified at a distance since they always travel alone.
Friendly AI[]
There are some AI units that are friendly and can be recruited to join the player. Friendly units typically travel alone and can be found all over the map, although there are certain areas where they are more commonplace. When a player is close to a friendly unit, the action 'Recruit' may appear on the mousewheel menu. When recruited, friendly AI units will follow the player and shoot at hostile units. They can be commanded in the standard ArmA manner.
Recruited units will have an icon in the bottom left of the screen. They can be selected with the function keys (F2 for the first unit, F3 for the second and so on) and given orders through the mousewheel menu or through the map.
If a friendly unit is order to remain in an area, that area will continue to be simulated whilst the player is off somewhere else.
Trader-type friendly units may travel in small parties, but neither the merchant nor his party can be recruited. The player, however, can sell or buy items from the merchant.