The end of the world has many forms, from asteroids to disease, war to time, the human race inevitably comes to an end in one way or another.
The infection spread through Europe, then into Asia, then the US, finally filling every crevice of the earth. This infection changed people. Turned them into monsters. An unstoppable force.
Spain was the first to collapse, Germany and Poland were next. The monsters invaded homes, ripped flesh from bone, tore families apart. Militaries were immediately destroyed as soldiers mutated and destroyed bases from within. The remaining population tried to fight back but they stood little chance and were slaughtered.
Now these monsters roam the earth slowly decaying into dust as the decades pass by.