Back in my AD&D days, pretty much anything published by TSR was considered "official", with Dragon Magazine articles often being referred to as "semi-official". Third party supplements, what little there were, were "not official" - they could be used by the DM, but pretty much never by the PCs.
The D20 / OGL explosion blurred many of the lines of what was / was not official for 3e, for good or bad.
With the OSR and the birth of clones / retroclones / simulacrums - there really isn't a definition of official anymore. Each ruleset is by definition a set of house rules, no matter how close they cling to their original brethren.
Actually, the strength of the OSR in my opinion is how fully the community embraces house ruling of the various rulesets. Make it your own.
Which is another reason I think I turned my nose at Tunnels & Trolls the first time I was exposed to it back in High School... it was being house ruled even back then. I wanted structure, and T&T wasn't structured like AD&D. I bought into the EGG line of "official play", but even the father of RPGs didn't follow that rule.
I'm happy to be playing games that embrace house ruling these days.
Monstrous Monday: Halflings are Half What? - I mentioned on Friday I am re-reading the Hobbit and Lord of the Rings. I am also likely to re-read the Silmarillion and even pick up some of Prof. Tolki...
2 hours ago