JudasIscariot: What options are you looking for exactly?
ERISS: My windows is Win10Pro 64b.
Once installed, in the shortcut TQ has only Unscale option activated (grayed too). I thick Compatibility to WinXP SP3, and Admin. Maybe there are better options, but, iirc, XPsp3 option (and Admin) is what I used with my old dvd version to play the better.
OK, so part of this can be solved using the "Show folder" feature in Galaxy :)
If you go to Titan Quest's page in Galaxy on your shelf and click on the "More" button, you will see an option called "Show folder". Click on that and that will open your file explorer exactly where all of Titan Quest's files are. Look for the games executable (should be TQ.exe or something like that), right click on it, select "Proerties" and within that menu you should be able to set the game to Windows XP SP3 mode and set the executable to "Run as Admin".