Make it so registered users have a page that has information about their account, and also where they can see an overview of the puzzle sets and puzzles they've done (suggestion: color coded green for done, yellow done with mistake, red not done, etc.).
Make it so registered users have a page that has information about their account, and also where they can see an overview of the puzzle sets and puzzles they've done (suggestion: color coded green for done, yellow done with mistake, red not done, etc.).