You can catch the whole Thief 1 playlist archive on YouTube, but here's some commentary and design themes that kept coming up:
- It's fun to get caught. Some of the best moments of the stream are when I've been detected by monsters or guards, and I have to run away and improvise some sort of escape route. If you play Thief yourself, I recommend avoiding the temptation to quick-load all the time, and just embrace the chaos. (Here's a big post full of tips for first-time players to best enjoy Thief 1.)
- The most beloved missions in Thief fandom are usually large missions with lots of different paths in open spaces, all centered around distinct landmarks and districts. (The Lost City, Return To The Cathedral) In contrast, some of the least enjoyed missions involve closed-off tunnels with only one or two possible routes. (Thieves Guild, Escape). This predicts a core argument for open world games: people prefer to play in large outdoor areas.
- There are a few basic Thief mission archetypes: city streets, mansions, cathedral, and the cave / tunnel / sewer festival. Later missions start mixing these types to surprise you and flip expectations -- city streets that lead you into a mansion heist (Assassins), spooky trap-filled caves that feed into a sprawling opera house (Song of the Caverns), or a cathedral that leads into monster-infested cathedrals underneath (Strange Bedfellows). These map genres show how Thief focuses on geographic fantasies and navigation patterns, instead of some sort of bland "delivery mission" vs "raid" typology.
- In the latter half of the game, the level design becomes more surreal and abstract, and that aesthetic leans on 1990s-era level design technologies. Being able to swim in an upside down waterfall, or suddenly step into an alternate dimension / starry endless void, both rely on BSP approaches to 3D geometry. These days it would be somewhat difficult to do either of those things in Unity or Unreal, because the technical norms for implementing visibility sets, water, and skyboxes have changed. (Water is usually a global plane instead of a volume, and skyboxes aren't secret ceilings anymore.)
- We remember Thief for pioneering systemic AI and stealth-based gameplay, but we've forgotten many of its smaller innovations. Games would do well to copy Thief's excellent use of symbolic and abstract map screens, especially the archaeology puzzle for The Lost City or the gorgeous map screen for Into The Maw Of Chaos -- or consider its sound propagation systems, which basically went uncopied until Rainbow Six Siege. (List of maps from Thief games.)
- The color palette and texturing in Thief is still amazing: dark saturated colors punctuated by bright accents, like all these deep blue and greenish-yellow stone walls with neon purple windows. Quake (1996) had relied on a fixed palette of 256 shades of brown / monochrome lights for the entire game... so you can imagine in 1998 when Looking Glass Studios got more colors and tinted lighting into their engine, they basically spammed color everywhere they could. The result is still striking, because in contemporary AAA we've gone back to boring blue-orange (blorange) grays for gritty style reasons.
What game will I do next? There's only one way to find out...