I will admit this is the 3rd time I've tried playing through thief 1, it definitely shows it's age but I think I got the hang of this go around and have reached farther into the game than before. It was thief: deadly shadows (3) that I first played and as you said it's really the fantasy/industrial aesthetic that pulls me in. As it is, I find the Thief series to be the epitomy of stealth games so I have to be in a very specific mood for them. If you grow bored of watching guards patrolling and waiting for the right moment to move or strike, then it would be really hard to enjoy. No supernatural powers like in dishonored to speed up the action.