The first project I ever made was a Poker app, so that was interesting for me
In the case of my Poker app it let me practise basic logic and gave me plenty of opportunities to apply that logic. For example: coming up with classes to represent Cards, Hands, The Game, The Deck, Users, etc.
As with any project like that, it's interesting to figure out the best design patterns and I remember refactoring my code several times throughout the process.
That worked for me anyway because I like poker, so I guess it depends largely on what your interests are. You like chess, make a chess app. You get the idea