The first 5 pages of Da Archive have the most of the older ‘un -maintained’ troves. The best thing is to go through them all soon and get what pdfs interest you.

I think specific smaller curated troves are easier to maintain than huge Collections. Check out Da Curated Archive to see what's in it. Pick a game or small publisher you like that’s not too big and complete it as best you can easily. Upload the pdfs somewhere. Hunt for and request the missing things. If it gets taken down, put it up again later. Using indirect links seems to work for Mageguru.

These are some Possible Candidates, based on modest size and perceived popularity. Most are in Da Archive, in various places and degrees of completeness:

13th Age 3pp Iron Gods 6d6 7th Sea 2e Abandon All Hope Aberrant/Trinity Aces & Eights Achtung ACK Action Movie World Advanced Fighting 2nd: Adventures in Middle Aeon AFMBE Against the Dark Yogi Albedo Alterkine Akashic Amazing Adentures Amethyst AMP Anima Anomalous Subsurface Environment Apocalypse World Arduin Arrowflight Ars Magica Ashen Stars ASSH Astral Empires Antlantean Trilogy Atomic Highway Babylon 5 Barbarians of Lemuria Barsoom/ Martian adventures Base Raiders BASH/BLAM Basic Role Playing Battle Century G/Z Battlefield Gothic Beyond the Wall Big Eyes Small Mouth Blades in the Dark Blue Planet Blue Rose Boot Hill Brave New World Broken Urthe Breachworld Bubblegum Crisis/ Dominion Tank Police Buck Rogers Bureau 13 Capes CAHS2 Cartoon Action Hour Car Wars Castle Falkenstein Castles & Crusades Cerulean Seas Champions Chill Clockwork Dominion Cold Hard World Colonial Gothic Conan Continuum Cosmic Patrol Crawling Under a Broken Moon Crimson Skies Crimson World Cryptworld CthulhuTech 2020 CYOA Books Cypher System d20 Modern d20 Future Daredevils Dark Conspiracy The Dark Eye Dark Fantasy Dark Future Dark Horizons Universe Dark Heresy Dark Matter Darwin's World Dead Reign Deus Vult Doctor Who Double Cross DC Heroes Degenesis A Dirty World Dragon Age Dragonball Z Dragon Kings Dragonmech Dragon Star Dragon Warriors Dream Park Dresden Files Dungeon World Dying Earth Dystopian Wars Earthdawn Eldritch High End of the World Eoris Essence Espionage Etherscope Everlasting Elric / Melnibone /Stormbringer Empire of the Petal Throne Encyclopaedia Arcane Engine Heart Esoterrorists Fading Suns Fairy Meat Fallout Fantasy Craft Fate Fiasco Firefly Fear Itself Freeport Fellowship Feng Shui 3ed Fireborn Flashing Blades Freeway Warrior Fringeworthy Folkloric Forces of WarmaHordes Fudge Full Metal Zero Game of Thrones GammaWorld Gangbusters Gary Gygax Collection Gatecrasher Gear Krieg Gemini Ghostbusters Giant Guardian Generation Geist Godbound Godlike Gods of the Fall Golden Heroes Grey Lotus Grim Tales Gumshoe Gypsy Knights Hacklopedia Hackmaster Harp (ICE) Harry Potter Helfrost Haven HeartQuest Hero Quest Hong Kong Action Theater In Nomine Iron Kingdoms Ironclaw/Jadeclaw JAGS - Wonderland James Bond Judge Dredd Judge's Guild Kaigaku Kagematsu Kalamar Ken Writes About Stuff Kingdom Death Kobolds Ate My Baby Kobold Guides Kult The Kyngdoms Labyrinth Lord Lamentations of the Flame Princess The Laundry Leagues of Adventure Leagues of Gothic Horror Legacy – Life Among the Stars Legend - RQ Legends of the Wulin Lone Wolf Low Life Maelstrom Mage Attacks Marvel Heroic RPG Mechanical Dreams Mechwarrior MERP Middle Earth Midnight Mindjammer Mistborn Mithras Monster of the Week Monsterhearts Monster Hunter International Mordheim Morrow Project Munchkins Mutants & Masterminds Mutant Chronicles Mutant City Blues Mutant Epoch Mutant Year Zero Mythic Vistas Nephilim Night's Black Agents Night Witches Noir Numenera Occult octaNe One Dice The One Ring Only War Osprey Other Dust OVA the Anime rpg Palladium Fantasy Paranoia Pendragon Pocket Universe Polaris Pony Stuff Porphyra Privateers and Gentlemen Protoculture Addicts Ptolus Qin Radiance Reign Renegade Legion Riddle of Steel Ringworld Rocket Age Rocket Ship Empires 1936 Rogue Mage /Spacemaster Runequest Scion Shadow of the Demon Lord Shadow, Sword, and Spell Shadows of Esteren The Shroud Sidewinder Six Gun Skybourne Skyrealms of Jorune SLA Industries Song of Ice and Fire Sorcerer Spirit of '77 Spirit of the Century Space 1889 The Sprawl Spycraft Star Ace Star Frontiers Stars Without Number StarSeige Starship Troopers The Strange Supernatural Swords & Sorcery Swords & Wizardry Tech Noir Tekumel TMNT Terra Ferax Terran Trade Authority Thieves World Thrilling Tales Thousand Suns Timemaster Tokyo Brain Pop Tokyo Heroes Top Secret Torchbearer Torg Trancers Transhuman Space Treasure Awaits Tremulus Tribe 8 Tri-Stat Truth & Justice Tunnels and Trolls Twilight 2000 Uncharted Worlds Underground Unhallowed Metropolis Unknown Armies Urban Shadows Valor Vanguard Victoriana Villains &Vigilantes War of the Burning Sky Weird War II Westerns Wheel of Time The Whispering Vault Wild Talents Witchcraft Wonderland-JAGS Wonderland No More World of Warcraft RPG World's Largest Dungeon Wurm Yggdrasil This is not a list of opinions, just games with at least 3 books and less than a jillion.

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RPG Magazines out there include Arcane Different Worlds Adventure Gaming Imagine Kobold Quarterly Owl and Weasel & Magazine Pyramid Shadis The Space Gamer Warlock White Dwarf (Early issues have Traveller, D&D, Runequest, etc.) White Wolf ??? https://archive.org/search.php?query=rpg%20magazine Thanks.