I was slumming over at TheRPGpundit's blog and saw him writing about three distinct waves of the OSR here.
- The first wave is devoted to retro-cloning original material from the 70's, 80's, and early 90's. An example would be Swords & Wizardry.
- The second wave is devoted to new RPG systems that incorporate large amounts of the original 70's, 80's, and early 90's material but take them in slightly new directions. An example would be Dungeon Crawl Classics.
- The third wave is devoted to taking that original 70's, 80's, and early 90's material (specifically the rules and game mechanics) into new settings, genres, and milieus. Examples would be Raiders! of the Lost Artifacts, White Star, Apes Victorious, etc.
Well, I'm here to tell you about the OSR's 4th wave...
4th wave OSR incorporates the spirit, tone, objectives, aesthetics, play-style, rules philosophy, mechanical principles, and hobbyist attitude from the 70's, 80's, and early 90's into RPG material that does it's own thing. Many consider these products neo-OSR, OSRish, OSR adjacent, or quasi-OSR because they've taken the next logical, evolutionary step away from original D&D, Traveller, Call of Cthulhu, Gamma World, Ghostbusters, Toon, Vampire: the Masquerade, etc.
While Kort'thalis Publishing started out with third wave adventures and campaign settings like Liberation of the Demon Slayer, The Islands of Purple-Haunted Putrescence, and Revelry in Torth, it soon went 4th wave with such titles as Crimson Dragon Slayer, The Outer Presence, and Alpha Blue.
Mechanically speaking, they feel old school (rules-light old school, not giant tomes with a rule for everything and everything having a rule without streamlined congruency old school), but they do not slavishly adhere to the d20 or systems that came before.
While I doubt that 4th wave OSR will ever replace the first 3 waves, it is my belief that the 4th wave is necessary for continued innovation. Even though I won't be basking in the popularity of core OSR, I have my place just outside where there's more room to breathe.