AbdulAlhazred
Legend
I'm curious whether Skills & Powers was literally considered "2.5" back when it was released. I was only playing intermittently at the time, but I don't recall anything like that. I've always been under the impression that "2.5" was applied retroactively to Skills & Powers when 3.5 came out.
No, and neither was UA (or OA, WSG, or DSG) in 1e. In all these cases they were additional rules, just supplements no different from what a Power book is today. Any existing 1e character was 100% identical even if UA was used at your table. There were options that you didn't have as a straight PHB character, ones you MIGHT like to have but nothing changed AT ALL. Obviously there was new stuff that you didn't have if you played with the old stuff.
Considering that the whole concept of 'edition' didn't even exist in the 1e days about all there was was a sense that UA presented a bunch of new stuff that if you used it would crank up the power level of some classes a bit. It was largely stuff that went right into 2e almost unchanged. Actually IME very few people USED UA and if they did it was more of a process of mining it for new stuff. As there was no concept of 'edition' back then there was also no concept of 'official rules' either.
Even with the various 2e PO S&P books there was STILL no concept of 'edition'. In fact I don't think I ever heard the terms 1.5 or 2.5 until maybe 3 months ago. For most players 2e in its entirety was just a largely compatible update of AD&D. In my group we simply started using 2e when it came out, there was barely a perceptible difference in characters. Combat mechanics changed some and a lot of monsters got a big power boost but there was rather little grumbling about 2e from a perspective of it being some big deal or changing the game radically, because it didn't really. Likewise the 2e power up books were just more fodder for those that wanted to use them or mine them for ideas.
The whole concept of official rules utterly did not exist in the community before 3.x. If you went to a con and played in a tournament then maybe in theory there were official rules for that, but 100% of that kind of play was pre-gen characters anyway.