You can. At some point someone (probably one of the original devs) released anonymously a vastly updated version of the Dark Engine that Thief (and Thief 2 and

You can. At some point someone (probably one of the original devs) released anonymously a vastly updated version of the Dark Engine that Thief (and Thief 2 and System Shock 2) used that not only fixed any issues of the original but added several QoL improvements like antialiasing, raw mouse input, widescreen support, etc and since then he makes sporadic updates. Look for NewDark. Sadly AFAIK he's still doing that anonymously through a french forum or something, probably because legally he shouldn't have the code. Despite that all modern re-releases of the games that used the Dark Engine (like those on Steam and GOG) are based on NewDark instead of the original engine.