I believe that your first game should 100% about learning about the program, and the different aspects of making games. So the game itself shouldn't be too hard to develop and complete in a polished manner.
Think infinite score games type games (tetris, runners, flappy birds, etc), and put sounds, music, graphics, interface, and then publish it somewhere people can play it =)
Your next game can be a little bit bigger and more complex.
Of course, all this assuming you haven't made a game before xD