Sphinx on 17/1/2015 at 22:28
Hold on. It truly wasn't my intention being rude, and I don't see what the fact that nickie is a moderator has to do with this, nor the out of context boss example to illustrate my presumably rudeness.
Yandros on 18/1/2015 at 02:05
In that case, there's obviously nothing more to say. As nickie said, we can move on.
snobel on 18/1/2015 at 09:21
@Sphinx: Which version of the game do you have? If the Sneaky Upgrade installer says that your game is not properly installed it's because the main registry key was not found.
Please, reply using more than one full stop per 150+ words. :p
Arcatera on 18/1/2015 at 11:33
If you have Steam version of Thief: Deadly Shadows, run the game for the first time (if you haven't yet), then apply the Sneaky Upgrade. This worked for me. Make sure you log out of Steam before patching and set the update priority for Thief: Deadly Shadows to "only when I launch the game".
Sphinx on 18/1/2015 at 15:42
After reinstalling the game it worked like a charm, apparently some registry keys were missing for some reason.
I installed the sneaky upgrade as well without any problem.
Thank you everyone for your suggestions though.