From the introduction:
The Idea. This game is based on the much less provocatively titled Searchers of the Unknown The root idea is, “What if the characters in D&D did not need more information than a monster’s stat block?” I enjoyed reading various interpretations, but I felt they clung too closely to their source material to please my sensibilities. So I did as any half-mad game designing genius would do —I made my own version.
Characters. These characters are stripped down to a basic level.
Fighter (simplified, and the simplest — the default)
Thirster (weak-blooded vampire)
Wizard (with a whole new magic system)
Martial Artist (not necessarily a monk)
Lightbringer (mortals with a touch of divine blood)
You should be able to take Strip D&D’s characters and rules and run B/X D&D scenarios with them. The monsters, magic, and treasure will be different than this version would expect, but that’s part of the fun.
Rules. The basic rules and a simple character sheet fit on one page. Combined with the specific rules for each class, that is all the player needs. The DM will want some good B/X or compatible scenarios to run.
Setting. The root concept of the game’s setting embraces the post-apocalyptic vibe of D&D. In this version, the world setting assumptions you have for D&D were true millennia ago. Technology and civilizations have risen, fallen, and vanished into dust since then. Multiple extinction-level events have transformed the world. Still, in some ancient corners only loosely connected to reality, or some areas sealed off somehow during all these ages, the old energies and creatures survive somehow.
In these ancient areas, there are highly endangered species that thrived way back when. (Elves, dwarves, halflings, etc. have been gone for thousands of years.) There are different kinds of magic than humanity uses now. Different enchantments on objects drive scholars to distraction trying to tease out their secrets. Also, some of the brave new corners of the world are extraordinarily dangerous, and require exploration.
The gods have abandoned this world, it has grown cold and dead-ish, magic was rebuilt to work in the new situation several thousand years ago and is now ancient in its own tradition. Into this chilly, abandoned world we see brave warriors mustering up the pluck to go into dangerous places after the lure of wonder and wealth.