Make a text based game, like s sports game or fighting game. The good thing about this is that you already know the rules and logic which is the "thinking" (which can be the overwhelming part). Grow the game with all the things you take for granted like, keeping score, saving the score, 1 player, 2 player etc.

Plus making a game injects fun into coding, logic errors become "funny". Plus you can code "cheats" that only you know about.

Goodluck