As Stormynature stated start with something like pong or even chess if you know the basic..
I think it would be much more motivating to start with projects you're interested in, rather than "standard" games like tic tac toe, chess, pong etc.
Or shop around and see what kind of indy/hobby games have been made in your preferred language, that you would enjoy making/playing. Try to reduce the game to the most basic state. Then, isolate the features that make up this basic game and try to produce tech demos for them. If you are able to do a demo for all of the features, you can then try to blend them together to reproduce the basic game.
By the end of this exercise, you would have made a basic version of the game you enjoy or want to make, and be equipped with the knowledge to add features or enhance it into your own unique game. Probably a more motivating endpoint than just making chess or pong.