In response to feedback from players of Thief, the team placed a heavy focus on urban stealth in the sequel, and they minimized the use of monsters and maze-like levels.

[1] Thief II is designed to be played methodically,[1] and the player plans ahead by scouting, reading the game's map and observing patrol patterns.

[13] In the aftermath of the Trickster's defeat and the failure of his plan to revert the world to a wild, primitive state,[2][9][14] a schism in the Hammerite religion spawns the "Mechanist" sect, which fanatically values technological progress.

[5][16] The game's primary antagonist is the founder of the Mechanists, Father Karras (also voiced by Russell), a mentally unstable inventor who despises the natural world.

[20] There, Garrett overhears Truart and Father Karras discussing the conversion of street people into mindless "Servants",[21] who wear masks that emit a red vapor capable of reducing themselves and any nearby organic material to rust.

[36] Viktoria plans to lure the Servants into the hermetically sealed Mechanist cathedral before Karras activates their masks, but Garrett believes this to be too dangerous and leaves.

[9] He explained that the team had played it safe by including certain "exploration ... or adventure oriented" missions with "jumping and climbing puzzles" in Thief,[11][42] and that the new game was significantly more focused on stealth.

[8][13] Based on feedback from players and reviewers of Thief,[8][13] the team decided to scale back the use of maze-like levels and monsters such as zombies in favor of urban environments and human enemies.

[8][41][43] Pearsall stated that Thief's monsters were negatively received because, unlike the game's human enemies, they did not clearly indicate when they noticed the player.

[45] Rich "zdim" Carlson and Iikka Keränen joined from Ion Storm's Daikatana team, and Looking Glass contractor Terri Brosius was hired as a full-time designer.

[42] Describing the work environment at the time, writer Laura Baldwin noted that "conversations dash madly about the room, [and] when someone is demonstrating something interesting everyone gravitates over to look.

"[47] During the first months of development, the team regularly gathered to watch films pertinent to Garrett's character and to the game's visual design, such as The Third Man, The Castle of Cagliostro, M and Metropolis.

[8][44][47] Pearsall said that the latter two films were Thief II's "biggest aesthetic influences", while the main inspiration for its plot was Umberto Eco's novel The Name of the Rose.

[9] The game's story was written in the three-act structure: Garrett was intended to transition from his "cynical self" in the first act to a private investigator in the second, and to a character similar to James Bond in the third.

[8][10] The City's technology and architecture were influenced by the appearance of Victorian London, and certain areas were given an Art Deco theme to provide "sort of a 'Batman' feel", in reference to the 1989 film.

[50] IGN's Jason Bates noted that the Thief II display attracted "a bit of a buzz and a small crowd of dedicated onlookers".

[53] The team used the new "occlusion" feature in EAX 2.0 to make Thief II's sound environment more realistic and to allow the player to listen through doors.

[55] The cutscenes, which Computer Games Magazine called "unique", feature multiple layers of artwork and footage of live actors filmed against a green screen.

[58] On February 24, Thief II producer Michael McHale announced that the game had reached "feature freeze", and that the team was in "super crunch mode".

[3] Writing for GamePro, Barry Brenesal commented that Thief II "provides a solid gaming experience" but "doesn't startle like its predecessor".

He wrote that its missions featured a "great deal of variety" and praised their "ability to casually suggest a much larger world", but complained that they were linear.

"[5] Jim Preston reviewed the PC version of the game for Next Generation, rating it four stars out of five, and stated that "Great, skulking gameplay, useful new tools, and clever level design make Thief II an excellent first-person 'sneaker'.

[58][66] The company had struggled financially since the commercial failures of its self-published games Terra Nova: Strike Force Centauri and British Open Championship Golf.

[75] In an open letter published after the company's bankruptcy, Smith wrote that the third game would have taken place in an "open-ended, self-directed city", and that its plot would have centered on the Keepers.

[66][78] This raised doubts that the Thief trilogy would be completed,[58][76] a situation that Salon.com writer Wagner James Au compared to Lucasfilm closing after the release of The Empire Strikes Back.

[79] On August 10, Spector commented that Ion Storm's first goal was to assemble a core team, composed in part of former Looking Glass employees, to design and plot the game.

[80] Thief II team members Randy Smith, Lulu Lamer, Emil Pagliarulo and Terri Brosius were hired to begin the project.

[88] Its plot follows Garrett (voiced by Romano Orzari in place of Stephen Russell) in the aftermath of an accident that leaves his protégé, Erin, missing.

[95] Brett Todd of PC Gamer US awarded it "Mod of the Month" and wrote: "It doesn't quite have the mysterious allure of the original games, but it's awfully close".

[93] PC Gamer UK's Kieron Gillen wrote that he had expected the mod to be cancelled, given that the "web is full of [...] five-percent finished masterworks from people who aimed far, far too high".