So, I have this weird problem with the graphics of Thief 1 and Thief 2 - but not Thief 3, or any other game that I play.

Months ago, I played through the whole series without any bad issues at all - except for the slowdown in some areas of Thief 3 which I am told is inevitable and down to weird issues with the engine.

BUT... I decided to try out the original couple of games again.

First time I tried to start Thief 1, I got a complete black screen. The sound happened but the screen was all black. I had to Ctrl-Alt-Del out to Task Manager and stop the program

Next time I tried to start it - and every time since - and with Thief 2 as well - all the colours have gone weird, psychedelic and swirling, both in the background of the menu and in the game itself I have no clue how this happened.

All I know is my computer is a Windows 10 one, with the latest updates (whether I want them or not, I don't have a choice in the matter), on which both games previously worked fine, and that I am not having any such issues on any other games, including those of similar age.

I tried reinstalling from my original downloaded install: I tried unstalling and reinstalling through GOG Galaxy: I tried uninstalling and reinstalling *again* from the new download version in April... The problem still persists.

Any idea (a) what might have happened, or (b) how to fix it?

yes - a win10 update, most likely. edit your cam_ext.cfg and change into and see if that helps.

Just done a test on that and it seems to have worked... thanks!

Forcing windowed mode seems to fix the problem too.
What I ignore is which solution is better. Performance wise the rgb10 solution shoukd be ideal if the game works better in full screen mode but no idea if it cuts image quality.

Any idea?

the image quality decrease should only be noticeable when using dynamic skies.

Thanks this worked.