It's essentially the "how do you eat an elephant?" question, isn't it? Hint, if you're not familiar with the reference, the answer is "one bite at a time."

I'm not a game developer (yet), but would like to try it, so I've done a little reading about the topic. There are a couple things I've seen advocated that have made a lot of sense to me:

1. Don't start with your dream game. Start with either tiny games to test specific aspects of your bigger game, or first practice developing clones of many relatively simple classic games, like pac-man, etc. This is a good resource I've found to help guide the latter approach: https://20_games_challenge.gitlab.io/challenge/

2. Don't spend a lot of time on either programming or creating art before you playtest the heck out of your game, preferably with many people. This is what I've seen advocated in a popular game design textbook: https://www.gamedesignworkshop.com/ - this makes sense since the same kind of advice applies to any kind of software development and design - verify that your potential audience is actually interested in what you are trying to make before spending a ton of effort making it. I've seen very similar advice given in the context of solo app development and even business startups.

Good luck and have fun!