The Far Away Land Adventures by Dirk Stanly are PWYW and virtually systemless. Really, they are a no-brainer pick up if you are an OSR gamer.
I talk briefly about Dirk Stanley's adventures for the Far Away Land RPG and using them with the ruleset of your choice. I also touch upon using Discord for running RPG sessions online. tenkars-tavern.games/Discord - tenkars-tavern.games/FALadventures (affiliate link)Link to Episode 88 - https://anchor.fm/tavernchat/episodes/Episode-88---Some-Free-Adventures--Using-Discord-to-Play-e20klr