Many people don't exactly check the "New Activity" page that often and miss when a game they participated in becomes a top game. I have a suggestion to add a Top Game badge for when it hits the Top Games as well as a Home Page bade when the game hits the Home Page. The badge would appear on the game itself. Users who participated in the game will also receive a notification when this occurs.
To make things even more fun, you could add a little accolades area to the user's profile that has a miniature version of these badges and the stats of how many top games/homepage games they have participated in.