Forget Pong, the new standard for a game to learn with should be making a Grand Theft Auto 3.

Third person controller, learn to swap over camera and controls to a vehicle when you enter it, learn how to make NPCs who walk paths and can be interacted with, learn how to make missions which are basically triggers and cutscenes and maybe an enemy spawning, mission complete increases your money. Learn to make police that chase you.

Easy. Simple stuff really. Elementary.

Don't want to do 3D? Then do GTA 1 which was topdown 2D.