Gamma Five Core Rule Book (2016)

A free, fanmade setting conversion for Dungeons and Dragons 5e

From the introduction:

Gamma World is a very special setting. First of all, it’s crazy, blending together sci-fi, fantasy, post-apocalypse, pulp narrative and humor. But there’s more to it than that. From its very beginning in 1978, Gamma World dared to thread on fears and anxieties that each and every one of us might face one day: nuclear conflict, radiation, aliens, the singularity complex. The seventh edition of the game, from Wizards of the Coast, based the (incredibly loose) storyline of the setting on an event known as the “Big Mistake”, an accident at the Large Hadron Collider in Geneva that shattered and then tied together all of Earth’s possible realities and timelines.

I always loved how, in Gamma World, we can face these fears with laughter and an overall tongue-in-cheek attitude, and this little rulebook will try its best to stay true to the rather whacky feel of the setting.