Some of my all-time favorites! I imagine there were precursors in terms of game design, but these were the first games I ever played where the enemy AI seemed actually intelligent. Like, guards would notice if you made noise, or if a torch had been extinguished. If they found the body of another guard they’d start searching for you. Pretty standard stuff these days, but that was a very fresh concept at release.

The studio behind Thief (Looking Glass) collaborated with Irrational Games on System Shock 2. Thief 1/2 and SS2 both used the Dark Engine, which leads me to my favourite piece of game dev lore/trivia. Because Thief was developed first, the game engine had code for sword parries. During SS2’s development they had persistent issues with that parry code activating when it shouldn’t. Testers would be trying to bean a psychic monkey with a pipe wrench and the monkey would parry with an invisible sword.