Tim Stellmach, the lead designer for Thief and Thief2, participated in a discussion about zombies in the game. In the comp.sys.ibm.pc.games.action newsgroup.
Lucian wischik wrote: Almost everyone who played the original Thief through to the end came to recognise that the zombie missions were good and interesting.
Joe62 wrote: "Almost everyone"? No they didn't. The Thief 2 design is a direct response to what Thief 1 users requested. They also admit that the "zombification" of Thief 1 was a concession to the Quake crowd, as the LG designers weren't sure the non-combat style of the game would sell.
Tim Stellmach said this: That's an oversimplification. First, the fact that we moved away from the use of zombies doesn't mean that people didn't eventually warm up to the missions with zombies in them. I don't really have any good data on whether they generally did or not (though clearly some people did). But if something about the game really puts off new players, I'd say you have to change it regardless of whether you think the people who stick it out will learn to like it.
Also, it was never primarily the "Quake crowd" with whom we meant to hedge our bets in Thief 1. Generaly, if you tried to play Thief like a shooter, you'd be dead pretty fast. Yeah, you could get away with it better with zombies and burricks, since they were slow-moving. But the monsters _were_ designed so you could sneak around them, not just have to blow them up. They largely failed at that with inexperienced players because their speech wasn't intelligible and there was nothing to really keep players away from a knee-jerk violent reaction, but you can sneak around them. The main difference between them and humans is really that they are so slow that they can easily be dodged around if you have space, which seemed like an appropriate tactic for a thief. It is true that we had more conventional (i.e. less strictly stealth-oriented) gameplay in mind for Thief 1, but that was designed around the trap-, quest- and exploration-heavy levels like Bonehoard, Return to Cathedral, and Lost City (respectively). And, by the way, I still like those traps, quests, and explorations: I think where the levels in question fall down, where they in fact do so, is in the details. Anyway, the main point of reference for non-stealth gameplay in Thief 1 was always action-adventure games like Tomb Raider, not shooters. The correlation between these adventure levels and "monsters" (zombies and burricks catch the most complaints) is largely coincidental.