Did you install these games OR did you just try and run them from the hard drive without installing them in the new operating system?
You need to install the games. You can install them to the same folder on the mech drive. The reason for this is that when you install a program, the setup file copies most files to the program folder however some files [usually .DLL type] are copied to the windows and or windows\system32 folder AND the registry is edited to show the location of these files.
While it is technically possible to make this work without installing the games, it requires a high degree of skill AND as I like to say, if you need to ask how to do the task, you do not have the skill level to accomplish the task.
In short, it would be much easier to simply reinstall the games.