RAID takes place in a science fantasy setting, inspired by other games, film, and literature.
Countless years ago, mankind spread itself to the heavens. Thousands of colonies and research facilities were established on hundreds of worlds across our arm of the Milky Way. History has forgotten what set off the technological enlightenment which allowed such feats as transmat relays, faster than light travel and century-long lifespans. Archeopriests have discovered that mankind colonized every world in our solar system within only a single century. Within three centuries, human life thrived in more than a dozen star systems. We know now that this Golden Age survived only a thousand years before something dark and terrible leapt out from the Hollow and struck our species into a new age of darkness.
The Dark Age hit all of humanity instantly. Still, our Archeopriests cannot decipher just what caused so much death and destruction across all of our colonized worlds. All otherworldly human life was snuffed out. The massive city upon the mysterious satellite known as the Skyshield is the last bastion of safety, however all knowledge of the technologies of the past were lost to us. The Jovian worlds, Jupiter, Saturn, Uranus and Neptune, once harvested for gases and energy are now home to great, floating graveyards. The Great Belt is a deathtrap; bloodthirsty aliens lying in wait behind every asteroid, ready to ambush unprepared adventurers. Mars, once a capital of engineering and manufacture is once again a desolate, frozen wasteland. Earth can no longer ensure humanity's safety, inhabited by savage aliens and wildlife run amok for centuries. Venus is a deadly environ of overgrown alien jungles, sky-scraping towers of the Golden Age, and churning, acidic oceans that wear away at the rocky coasts. Mercury is a fiery-hot dungeon, carved full of subterranean fortresses and caverns dug by Orc invaders and inhabited by a menagerie of monsters from across the galaxy. It is a galaxy of immense evil and unimaginable horrors, but it as also a galaxy of magic, treasures, and wonders to behold.

RAID utilizes a unique, 3d10 "roll under" system, inspired primarily by the Dragon Age RPG and Fantasy Flight's 40k RPG series. Exploration and combat are reminiscent of D&D 3.5 and Pathfinder. Though there is not a "class system", players may choose to adopt multiple "Archetypes" which allow them to gain abilities through Archetype Ability Trees. After gunplay, Psionics are the second most important part of RAID's combat system. Psionics are magics, accessible to many, though mastered by few. Leveling up is meant to be fast-paced, allowing players to experience a wide array of abilities, weapons, psionics and foes within only a few sessions. Overall, the goal of RAID's design is to provide a fun ruleset that immerses players in the universe.