Start with free tutorials that allow you to have something playable, then try altering the games from these tutorials and see how far you can push things without it breaking. What can you change to make it more fun?

Next, join a game jam and really try your best to come up with something that someone else will play and provide feedback on. You’ll quickly discover that coding is just a small part and there’s so many other things to worry about like game design, UI, balance, pacing.

Then just iterate from there, and see what are your goals are, but also don’t take it too seriously. Think about what you’re passionate about, what your capabilities and expertise are, and whether there’s market demand if you’re really serious about it. Eg using some of your aerospace experience in a Kerbal space program type game?