Metagame
Metagame consists of the off-screen simulation of events and interactions of NPCs and Zombie between themselves and their environment. The metagame becomes concrete when the simulated characters and events come "on-screen."
For example, the gunshots heard and the helicopter or airplanes passing overhead are metagame events. Currently, however, the player can't find who fired the gun or where the helicopter or plane went. The dead will still follow the sounds, sometimes passing (or eating) the player, originating from somewhere off-screen.
Helicopter Event
As of build 33, the Helicopter Event was added to the game as a physical object that is unable to be seen but can be heard. This is one of the first metagame events to actually influence gameplay in Project Zomboid. The helicopter can be heard overhead and, if the player is outside, will follow the player around leading hordes of zombies towards the player. If the player is inside when the helicopter arrives and does not go outside, the helicopter will not follow the player, given it does not spot the player through uncovered/unbarricaded windows. This can be accomplished by listening to the Automated Emergency Broadcast System which can be tuned to on a radio. The channel for the AEBS is randomized, unlike other pre-set channels. The helicopter might come around twice so staying inside for the entire day is advised if adopting this strategy. The zombies will still migrate slightly so beware. If spotted outside, the event can be detrimental to players with secluded bases as it can very quickly lead large hordes to locations they wouldn't usually go to.
Future Metagame
In the future, the metagame could involve complex interactive storylines, influenced by the environment, random events, NPCs, or the player. Most NPCs, however, would just be random survivors just trying to make their way. But certain NPCs would have storylines in which they make AI decisions and have scripts; the decisions and scripts would change depending on random chance or input from other NPCs, the environment, or even the player. For example, in the Kate and Baldspot story, the player could take the position of the raider. Presumably, the raider-player could threaten Kate, kill Bob (or do something else). In other words the player takes part in the storyline, becoming a participant in the script and thus changing the script, NPCs, and the metagame.