Why don't you start with an idea and self-awareness of your strengths?

You might be good at puzzles. Or stories. Maybe visuals ain't your thing and you can write a text based game - there are great engines for that. Maybe you're a great dev and can start hack your own Dwarf Fortress and keep on doing it for the rest of your life.

Gaming and tech behind is so varied that whoever you are, you'll find something that plays to your skills.