my suggestions:
when the user logs in, store the login time in a "visits" table - along with the user's name.
in your game script(s), include a routine which calculates the time passed since the visits entry. if it is more than an hour -> display "oops sorry, wait for tomorrow".
if it is another day than the one stored in the "visits" table, delete the past visits entry and write a new one.
this is a database + login-based solution, no cookies/session necessary.
hope this helps!