Meanwhile, he managed to introduce his personal creative stamp in the Ultima universe, by developing new games which bore the Ultima title, but were decidedly autonomous from Garriott's richly-detailed (but by necessity for everyone except Garriott, creatively restrictive) world. "I always told the teams, 'We're going to set this up so Rich can't ever say, 'that wouldn't happen in Britannia!'  So 'Martian Dreams' was set on Mars in the 1890s... 'Serpent Isle' was set in, well, Serpent Isle... It was all part of my cunning plan to take advantage of the history and tradition of Ultima without being constrained by Richard's (totally compelling) vision."

Spector was involved with the Ultima Underworld series

While still attached with Origin, Spector worked on his first title with Looking Glass Studios (Blue Sky Productions at the time), an Ultima-based title whose influence on game design would far outstrip its achievement as a CRPG, or even a first-person game -- "Ultima Underworld", after all, was both.  The title is so thoroughly innovative, it's surprising to think that it was sold at roughly the same time that the "Wolfenstein 3D" demo first made its appearance.  But unlike Carmack and Romero's unrelentingly horizontal shooter, the Stygian Abyss was a world fully conversant in the X,Y,Z axes: it had ramps you could walk up and down on, rivers you could swim, high overhangs you could fly to.  The interface allowed you to customize your character to a remarkable degree, yet it felt more intuitive and organic than the more traditionally conceived pen-and-paper RPG archetypes Richard Garriott employed in his own Ultima titles.  (And years before "Diablo", Spector's team represented mana and hit points in terms of red and blue liquid vials.)

System Shock quickly became an underground favorite in 1994

After Underworld's sequel, his next collaboration with Looking Glass was even more revolutionary: 1994's cyberpunk-tinged "System Shock", which many gamers will defend to their death as the greatest game ever made.  It featured the "cyber-interface", a heads-up, computerized grid worn by the game's hero, keeping you apprised of his health, stats, and material inventory.  It was a brilliant way of conveying in-game information in a way which didn't feel like an artificial imposition on the world.  And while it seems like an application of Spector's design principles, he accords credit to the cyber-interface to Doug Church and his Looking Glass team.  He was, however, instrumental in Shock's devious workaround to a nagging design challenge in CRPGs: how to create believable player interaction with non-player characters:

"We killed everyone off," says Spector.  Instead of jiggering with cumbersome dialog trees or conversation topic lists, you moved through a space station where the only other humans around were stiff as boards: "The inhabitants of Citadel station would exist, for the player, only through e-mail and video logs," he wrote in Gamasutra.  "It was an elegant solution to an intractable problem: if we can't make you believe you're talking to a real human being, we just won't have any in our game world."  Another Spectorian innovation for "System Shock" is a maneuver which seems so obvious in retrospect, it's astonishing that so many first-person designers hadn't thought of it before (and usually don't, still).  I speak, of course, of "the Lean".