Man that’s quite the list and more than a few of them are enigmas to me! I’m riding the train but I’ll try to think up my list later!

The Knock zines for sure.

Going to add 4 More

Sandbox Generator

Table Fables I & II

Fight On! - The definative OSR Magazine https://www.lulu.com/shop/ignatius-umlaut/fight-on-compiled-compilation-4/paperback/product-1k8g2q56.html?q=fight+on&page=1&pageSize=4

Gardens of Ynn created a new way to dungeon crawl - don't believe me try it out for free https://quirky-kirch-a6f314.netlify.app/

This list is awesome, and a number of the things on it are also things I keep in my collection. I'll just list the ones that I didn't see here that I use often. The comparison to "official" D&D books is just to state how I typically use them

• PHB: Whitehack (4e just came out but it looks largely the same as 3e with a few changes to, I think, excise the OGL)
• MM: Bestial Ecosystems Created By Monster Inhabitation
• DMG: Maze Rats (it's a whole game, but it's also the best low profile Dungeon Master's Guide that exists.

Splat books would include:

• Basically anything Lost Pages has put out (Magic supplements)
• The Nocturnal Table (DMG but for city adventures)
• Vermis I (Setting Guide/Mood Board)
• On Downtime and Demesnes (Another DMG supplement)

I don't use them all for every game, but I love having them all on my shelf for anything I might need during prep.

Also, a shoutout to the OSE Classic Fantasy Rules Tome. It's so nice, and even if I'm not playing it, there's a great selection of magic items and other random stuff for the DM, and like...it's a really nice looking book.

I'd add the following:

The Black Hack

The Metamorphica - a fun book of tables of mutants, chaos stuff, and weird technology

I tend to focus on products which go against certain "maxims" of play; having alternatives to some of the more strict rules inherited from Gygax offers insight into the philosophy behind certain rules and whether such rules are actually fun at the table.

The Black Hack is my go-to book for this purpose: distances are relative, consumables are abstracted to the usage die, experience is based on stories told and not treasure dragged back to town, and all of the dice rolling can be made by players if the GM so chooses. Such a free system allows for easier hacking; You don't need to compare relative power of classes when determining how much XP your homebrew needs in order to level up.

For supplements and splatbooks, I particularly like Wonder & Wickedness and Marvels & Malisons as magic supplements. It's easy as hell to slap together a sorcerer class from these two books and staple it onto the Black Hack. My favourite setting books are Ultraviolet Grasslands and Hot Springs Island; both offer perfect sandbox adventures for the Black Hack. Both offer some manner of departure from the traditional tropes of TSR adventures. I have had to modify some aspects of the latter, such as the

There are a stupid number of blogs and zines that I could namedrop, but the one I find myself agreeing with the most is The Alexandrian.

• Swords & Wizardry, Complete (English and Herman versions) and White Box

• Time of Adventure Design

• Knock! 1-3

Adding 1 more!

Don't know how I forgot this Zenopus 20 Backgrounds for OD&D https://zenopusarchives.blogspot.com/2014/08/20-backgrounds-for-od.html

Add a Few More from the Grim Dark World

Small but Vicous Dog https://vaultsofnagoh.blogspot.com/2011/07/small-but-vicious-dog-steals-hearts.html

Warlock https://www.drivethrurpg.com/product/312204/Warlock

In The Dark Zine https://feral-indie-studios.itch.io/vast-in-the-dark

The Free 2011 LotFP Referee Book - https://www.drivethrurpg.com/product/148012/LotFP-Referee-Book-old-Grindhouse-Edition

The Best of White Dwarf Scenarios I,II, & III are must owns