Fan Casting Post-Godzilla

It is the future, the world was devastated for decades since *the present*, the year the world had destroyed each other with nuclear weapons trying to kill Godzilla. 95% of humanity was wiped out, and only a few survivors went underground. Earth became Hell, and Godzilla punished them all. The last surviving members of mankind discover a shining beacon of hope: a untriggered weapon from 1954 called the Oxygen Destroyer. A small group ventures out from their underground hole and into the bottom of the sea, where the Oxygen Destroyer still lies. To destroy Godzilla will restore their world, or so they think.