The original. This is a good version, was developed with original Thief 1 in mind. Change the gamma to your liking, this is made to be dark and atmospheric.

Made using Black Parade Mod, it may look great on original Thief, I have not tried yet. Rewrite of many aspects, this version has no Ambient Occlusion, however the lighting has a higher bit-depth. Change your gamma to your liking.

Made using Black Parade Mod, see forum post about removing the watermark. This version has Ambient Occlusion, however the lighting has a lower bit-depth because it needed special DirectX6 conversion files for Occlusion. Change gamma to your liking.