Change Google Play password without changing Google Account password Is this possible? I want to just change my Google Play password without changing my password for every other Google product.  

Basically I want to allow a friend to log-in to some of my mobile game accounts, but not give them access to my entire gmail/google account..
Quick Answer: No

Your Google Play store account is tied to your Google Account if you'd like to share it with someone you'll have to share your Google Account. There is no such thing as a Google Play store account only a Google Account.