Would be great to incorporate more modern game design techniques to boost replayability and how much people want to share the game with their friends.
Some ideas:
Achievements: encourage folks to log in, store with their account. Example achievements: Complete the first tutorial, complete all tutorials, win each of the scenarios, win at each difficulty level
Improve leaderboard: Let people enter username, show names on the board, celebrate scores at end of each game
Perhaps with the above, there's a new main menu item for achievements, that shows your scores, earned badges, and progress towards unearned badges? (like Steam achievements page)
On the scenarios list page, if you're logged in, indicate which ones you have/haven't played yet (perhaps by showing your best score vs the global high score?)
Would be great to incorporate more modern game design techniques to boost replayability and how much people want to share the game with their friends.
Some ideas: