Yeah the -dontforceminreqs fix did not work for me either. Obviously this game does not run on Windows 7 like the min requisites implies.
I ran the game on WIndows 7 64-bit without any problems, so that's not the issue.
Make sure you are making a shortcut to the correct file. You do NOT want to run the game's launcher, you want to run the actual withcer.exe file. Navigate to the install folder, find witchter.exe, make a shortcut to it, and then add the -dontforceminreqs tag to the end of the target field for that. Then run it from that shortcut.
Post back if that still doesn't work.