You could use ‘Regshot’ which takes a snapshot of the registry before and after installation:

Just unzip the archive, locate the ‘regshot.exe’ and run it then do the following:

1. Click the ’1st shot’ button and choose ‘Shot’ then wait for the ’2nd shot’ button to become active, don’t Click it yet!
2. Install the game!
3. After the game has installed completely then you can click the ’2nd shot’ button, choose ‘shot’ and wait for the ‘compare’ button to become active.
4. Click the ‘compare’ button, you will get a notepad listing of all the registry changes, just save that list from notepad and zip it up and share it!

This will easily show what registry changes the game has created.

Regshot