>>530922646
Plan out the smallest scope game you could possibly make. Then cut the scope in half again.
Don't think of it as making shovelware for a quick buck, but rather as making the base framework that will allow you to iterate and expand your original concept into ever increasing larger games.
See pic related. For many years I thought I should make the top, but only recently I realized that I should have done the bottom as a solo developer. Building a car from scratch takes too much time, it's better to start by selling bikes and build your car factory with the money earned along the way.