The children realize that their latest fight is no where on Earth, at least, not the one they know. The awful truth behind the game comes out.
In other words, it's an 
alternate future Earth.
.بمعنى آخر، أرض تعود لمستقبل بديل
Also auf einer anderen
Erde aus der Zukunft.
En somme, un futur alternatif.