Aftermath! is a role-playing game created by Paul Hume and Robert Charette and published in 1981 by Fantasy Games Unlimited.
Aftermath! cover art
Gamma World is a post-apocalyptic science fantasy role-playing game in which player characters explore Earth centuries after the collapse of civilization, searching for artifacts from the time before "The Great Upheaval". The game was originally designed by James M. Ward and Gary Jaquet, and first published by TSR in 1978. It borrows heavily from Ward's earlier role-playing game, Metamorphosis Alpha.
Gamma World 2nd edition Basic Rules Booklet cover