Nightdive Studios' upcoming remaster of Looking Glass Studios' classic stealth game, Thief: The Dark Project, has provided an unexpected glimpse into the original development of the title and its groundbreaking Dark Engine. Software engineer Josh Dowell shared insights from a "very very out of date version control repository" for the game's code, which revealed a tumultuous development history.
Dowell described the unearthed code comments as containing "the wildest things to say about the code," with programmers leaving messages like "Giant hack! Never replicate this! We must fix this before '98!" and "E3 hack! We must delete this after E3!" These notes suggest that development was rushed, with teams working on different projects and code being patched together under tight deadlines.
The Dark Engine, which powered both Thief: The Dark Project and Thief II, has long been praised for its technical achievements in audio, AI, and lighting. Dowell highlighted that the engine's rendering and level technology are surprisingly similar to those used in id Software's Quake. "Thief's rendering and the technology that powers the levels is, shockingly, it's just a clone of Quake," Dowell stated. "The way they do the lighting is exactly the same as Quake, the way that lights are turned on and off is Quake."
While the underlying principles are similar, the Dark Engine's implementation is remarkably complex. Dowell explained that instead of Quake's precomputed visibility, the Dark Engine employs a real-time portal system. "It's super complicated and I can't believe they got away with it in '98, because it's doing the thing that Quake did that was slow, but it's doing it in real-time," he remarked.
The Thief: The Dark Project Remastered is currently without a release date, but progress can be followed on Steam, GOG, and the Epic Games Store.