Indeed, pointing to Appendix E as proof that Thac0 was a part of AD&D is like saying that "Less than Zero" was a Brad Pitt movie. Sure he was in it--according to Imdb he was an uncredited partygoer--but it's only on because 2e adopted Thac0 full on--or so I gather--that this gains any significance at all. If 2nd edition AD&D had gone with ascending ACs and to hit bonuses more akin to Castles & Crusades, et. al., Thac0 would be as familiar to us today as all those other party-going extras who did not become Brad Pitt.
|Thanks, but what's my Thac0?|
But obviously the Appendix E reference indicates that there was something going on with Thac0. But did anyone outside of a posse of computer science majors at UCLA and a few Lake Geneva insiders actually know what Thac0 was supposed to be used for? As a kid, I assumed that it was listed to give a measure of relative combat acumen--just as AC is a measure of defensive capacity--that could, in a pinch, be used to recreate the combat matrices. Why anyone would bother doing such a thing was beyond me since the matrices were readily available on every DM Screen that ever partitioned a gaming table.
But I could be totally wrong. My sample size is not large; maybe loads of people were using Thac0 back in the day, despite TSR's refusal to endorse it. Is there anyone out there that was into Thac0 before it went mainstream? And what was the first TSR publication that actually explained what Thac0 was all about?