A project I worked on awhile ago using LibGDX and the engine I made for FlyBy was an asynchronous multiplayer minesweeper game based off the MSN instant messenger game Minesweeper:Battle. I decided to try creating an asynchronous game as at the time I had never worked with databases before and it seemed like a fun challenge. I chose minesweeper because it is a game with very simple game logic, which would allow me to focus more on the asynchronous aspect of the project.
Since I had the project lying around with no intention of doing much with it I decided to open source it in the hope other people who want to try something similar might be able to take away some value from it. The end result used three different database tables. One for accounts, matches, and player turns. The structure for the tables is included in the repository as well as all the SQL files in the SQL folder in the root of the repository.