Something that I have tried in the past... rather than building two whole seperate games, start on the project you want, but severely compartmentalize it. For example, say you want to build the zelda-style game you are talking about. Pick an ending point (which may be harder for you, because those types of games dont really haev defined levels) and make that your first project. After you have reached that ending point, and are happy with what you have, move on.
A word of warning though: it is very easy to get overwhelmed if you dont focus only on your goal. You can start thinking of the big picture, which is bad, and just want to quit when progress is slow. However, for the well organized and tunnelvision-gifted, it works nicely, because not only do you learn with a smaller project, but you are already that much closer to your larger project.
Anyways, just a thought,
Jay Watergate