Started on the one that started it all - Arena on DOS obtained at some hole in the wall PC store off the shareware rack with Doom. If you've seen the box cover, and the warrior chick in the bottom center, you'll understand (if you're a guy) why I had to be a part of it! The first, still the best, as I say in the Skyrim thread. It can only be unheard of "WTF" new once. After that each game was a natural progression of a company proven to be hardcore pushing the envelope. But when Arena came out it instantly put everything else, like Ultima, King's Quest, et al, to complete shame in a way that will probably never be possible again.
Since then I've bought every TES game the day of release except Redguard, which I didn't buy at all because it sounded like it was going in a completely different direction from where Arena and Daggerfall was taking the experience customization. Best gaming experiences ever. Best money I've ever spent on a computer game.