Minecraft
The digital realm of Minecraft exists in a state of theoretical immortality. World saves, compressed into folders of modest size, may persist across hardware generations through the simple expedient of file transfer. A structure built in 2012 remains architecturally sound today, assuming one has maintained the appropriate backup protocols.
However, this durability depends entirely upon the continued existence of compatible systems. Should the electrical grid fail, or should Microsoft's servers experience what technicians euphemistically term a permanent outage, these worlds would vanish as completely as Atlantis beneath the waves.