Create a website like: [login to view URL]
It's a Football Management Game.
All the features of the above example should be implemented and it should have more options as well.
The main idea about a Football Management Game is that you can buy/sell players, play matches against other members, build a stadium and facilities and so on.
Please check other Football Management Games to see what options are possible to implement.
For example a difficult part is to calculate what happens in a match. The two teams are made by the two users. They play against each other and there should be calculations on when a goal is scored, when a change is created and so on.