In M9BOOK.STR there's a reference to the Dragonslayer movie. In the movie, an elderly servant Hodge (Sydney Bromley) dies, making to say that Urland's ashes must be spread over "burning water". In M9BOOK.STR, there's a passage about a Keeper called Hodge that died, and his last words were "burning water".
- If I had a Hammer...
In the mission Strange Bedfellows, you can find a book which says: "Hadst I a hammer, wouldst I hammer in the morning. Wouldst I hammer in the evening, all over this land." This is a reference to the opening lyrics of the song "If I had a Hammer".
- Tomb Raider
In the mission Down In The Bonehoard, when Garrett enters the Bonehoard, he says, Time to... Raid some tombs...
- Terra Nova: Strike Force Centauri
In the cutscene where Garret meets Constantine (CS06.AVI), the bottle of Biddleybong includes the text "Bottled at Centauri Vineyards, New Hope". In Terra Nova: SFC, NewHope is one of the planets of the Alpha Centauri system that has been colonised by the Clans.
Both the 1909 Gaston Leroux novel and the popular 1980s A. L. Weber musical (loosely based on the novel) are given nods throughout "Song of the Caverns". The informant Giri (Madame Giry and her daughter Meg Giry), Raoul (vicomte Raoul de Chagny), Lady Valerius (Madame Valérius, elderly guardian of Christine Daaé), etc.
One Thief fan even went to the trouble of making a whole music video homage to the musical version, involving still images from "Song of the Caverns", and TDP and TMA.
- Romeo and Juliet
The script of a play found by (and dismissed verbally by) Garrett, about a young Hammerite and a female pagan spirit falling in love, is a clear riff on Shakespeare's Romeo and Juliet, and many similar "star-crossed lovers from warring factions" stories.
To the south, next to the canal off of Helena Way, there is a wooden "W" on a wall, with three torches. In the canal below the "W" is a coin purse.
Plagiarizing Azal's explanation: In the 1963 movie It's a Mad, Mad, Mad, Mad World, the character Smiler Grogan buried a large amount of money beneath a mysterious "Big W", and the big race for the hidden fortune formed the basis of the movie.
Several former developers at Looking Glass Studios admitted that one of their sources of inspiration for the stylistics of Thief: The Dark Project was Umberto Eco's 1980 historical crime novel The Name of the Rose. One example in TDP and TMA would be the default texture's nickname, "Jorge", based on the name of a character from the novel. There are, of course, plenty more similarities... Especially in TDP and TDS.
As late as Thief: Deadly Shadows, this literary influence seems to have something of a resurgence. There are several details concerning the Keepers, including the architecture of the secret Keeper Compound and the contents of some of its library's readables, that are possible nods to the storyline and setting of Eco's novel.
In Deadly Shadows, the Keeper Compound's interior seems to be inspired by elements of the abbey from TNotR, the main setting of the novel. The abbey is home to a huge and ancient library, with an octagonally shaped internal and external layout and many vertical levels, the building built in the manner of a tower. This is exactly identical to the internal appearance of the TDS compound's towering central hall, with its octagonal layout, and many alcoves spread across all of the eight walls, at each vertical level of the hall.
In the film adaptation of the novel, the staircases connecting different sections and levels of the library were often portrayed as intertwining with each other, in a fairly complex pattern. This sort of portrayal does not seem to appear directly in TDS, but is very prominent in a TMA cutscene when Garrett agrees to visit the Keepers and witnesses Caduca's and Gammall's prophecy reading.
A readable coded "KCbafford", found in the Keeper Compound during the later events of Deadly Shadows:
Keeper Emory, I spied an initiate reading the Bafford Chronicles in the Dining Hall this eve. Such travesties of the written word may have their place in a nobleman's store, but are inappropriate here. The monetary value of this book matters not to a scholar. See to it that the book is removed from the hall and destroyed.
Though this is also a reference to the often comical Lord Bafford, it distinctly mirrors a scene from the novel. In the chapter Day Six, After Terce, the young monk Adso reminescences to his mentor William about certain frivolous pieces of fiction, read by bored monastery dwellers, despite prohibitions:
William listened to me in silence, then asked me, 'Do you know what you have dreamed ?' 'Exactly what I told you', I replied, at a loss. 'Of course, I realize that. But do you know that to a great extent what you tell me has already been written? You have added people and events of these past few days to a picture already familiar to you, because you have read the story of your dream somewhere, or it was told you as a boy, in school, in the convent. It is the Coena Cypriani.' I remained puzzled briefly. Then I remembered. He was right! Perhaps I had forgotten the title, but what adult monk or unruly young novice has not smiled or laughed over the various visions, in prose or rhyme, of this story, which belongs to the tradition of the paschal season and the ioca monachorum? Though the work is banned or execrated by the more austere among novice masters, there is still not a convent in which the monks have not whispered it to one another, variously condensed and revised, (...) others encouraged its circulation because, they said, through its jesting, the young could more easily commit to memory certain episodes of sacred history. (...) And how many scoldings had I received from my masters when, with my companions, I recited passages from it ! I remembered an old friar at Melk who used to say that a, virtuous man like Cyprian could not have written such an indecent thing, such a sacrilegious parody of Scripture, worthier of an infidel and a buffoon than of a holy martyr. ... For years I had forgotten those childish jokes.
Given the very monastic trappings of the Keeper faction, their central role in the story of Deadly Shadows, and former LGS devs' direct participation in the writing and making of the game, it's quite possible these were meant as oblique but fun references to Eco's novel.