Is there an overview of all stamps for all games somewhere? So far, my only option is to access (and start playing) every single game in order to see what stamps I am missing, which is quite annoying.
Unfortunately, I don't think there is a stamp overview page. However, as a low-tech solution you could note on paper which stamps you have completed, like this:
Air Sports: (x) (x) (x) ( ) ( )
Archery: (x) ( ) ( ) (x) ( )