Invasion

The world had become used to the metahumans - people sometimes perfectly
ordinary,but sometimes quite extraordinary in appearance - who mostly
worked with their governments as high-powered peace officers, fighting
crime, and sometimes fighting rogue metahumans who had become
super-criminals. Then that comfortable world ended in just one
terrifying day.
Suddenly, all world governments were
simultaneously attacked by soldiers in giant mecha robotic suits with
the swastika symbol of the Third Reich on their metal arms. If these
were Nazis, where had they been hiding since the end of World War II?
And where had they gotten armor and weapons far in advance of anything
on the planet? Weapons against which even the metahuman heroes seemed to
be helpless . . .