Ultima VI is was really got me into coding world simulations, but Ultima VII really showed the potential of the genre. I think that's why Ultima VIII and IX were such a disappointment.
The interactions, exploration and focus on virtues that hooked me into these games. I could care less about the graphics if these elements are well done in the new game.
Ultima VII was a wonder to me when it came out.
I was stuck in the Apple world so I stopped playing after U5. I bought the Ultima-giftpack on GOG.com before Christmas, but still have only had the time to work through the first 3. I'm savoring them, still.
I had it as the NES cartridge, mostly oblivious to the franchise's history on the computer platforms. I also had the Game Genie cheating device, whose codebook had a fairly rich set of codes for the game, changing your characters' health and stats and such. There were enough closely related codes (30 strength, 60 strength, 90 strength) that I started seeing the patterns, working out how the Game Genie code letters mapped to bits and represented the data values. So then I started synthesizing more codes that weren't in the book: hey, adding one to this letter changes the next stat instead, that must be a memory location. What happens if I add 16 to it, nice it changes the next character.
Ultimately I never really played the game with hacked characters, since the challenge of the game wasn't the stats but in exploring and mapping the dungeons and hidden areas. (I had nightmares for years about getting lost in Ambrosia.) Other NES games were much more interesting with hacked stats, notably Final Fantasy I.
Ultima III on the NES also contained the first major loophole exploit I discovered in a game. When in a dungeon, your magic power would slowly recharge with every step, but also risk running into a monster encounter. But I happened to realize that _rotating in place_ did the former and not the latter. So just by pressing the right arrow 300 times between encounters to recover 75 MP, you could cast the top-end magic nuke spell on every single monster group, virtually achieving god mode.
In dungeons, if you were standing on a location already holding something (chests and strange-winds, basically), a monster couldn't show up, because it would have no place to drop its treasure chest.