I came across a good article on a path to Game development. It seems the original site is now non responsive, but the web archive of it still exists. This short article was a recommendation from an indie game developer about a series of game clones to try to complete in an effort to learn by doing. The article is from 1999, but I think it has some good suggestions. The idea is that you create these clones from your knowledge of the games listed and to make a complete game out of each. The games he suggests are
A Tetris type game
A Breakout type game
A Pac-Man type game
A Platformer (Super Mario type game)
He gives reasons for each and this seems like a good path. He really stresses the importance of making each of these into a finished working game, so that you have the experience of FINISHING a game rather than starting one, over and over.
The original article is here on the web archive.