Instance Lifespan

Instances can have lifespans.

Two main types of lifespan? Absolute, and population-based.
Absolute lifespan is a set time; when this time is reached, the instance will automatically close. This could be real-life time, or it could be Minecraft in-game time; EG 'dawn'.
Population-based lifespan is a period of time, such as five minutes. If the instance is empty of players for this long, it will automatically close. Players re-entering the instance before time runs out will reset this timer.