The Day after Ragnarok is a setting released initially for Savage Worlds, and has subsequently also released in a version for Hero System Sixth Edition. The concept has been described by the creator as "Conan 1948".
The world is an alternate history that follows very similar to our own until near the end of World War II. When the Nazis try to recreate the world by initiating the Norse apocalypse Ragnarok by summoning Jörmungandr, , the USA uses it's limited atomic bombs not to attack Japan but to kill the giant serpent.
Three years later the giant body of the Midgard Serpent still lies across Europe and Northern Africa. There is a President of the United States in California, but he is not fully recognized by Texas or Utah. Only a few city states still exist in North America east of the Rockies, the lands poisoned by the Tsunami of salt water and venom from when the serpents head fell in the Atlantic. Stalin has pillaged what is left of Europe East of the serpent wall. What's left of Cornwall and Wales still swear to King Henry IX in Sydney, the now capital of the battered British Empire. All around strange creatures have emerge and technologies strange to us have been developed.
An earlier version of some parts of the game concept was publish in Pyramid Online Magazine (May 18 2007) as "The Day after Ragnarok: Reality Urdha"
also see The Day after Ragnarok (HERO System 6th Edition)