Game Development

A Quick way to test ideas to see if they would be fun is by making a pen and paper prototype or making a MVP (minimum viable product) prototype in a game engine.

If you use a game engine to build your prototype - make it very simple, only basic shapes and focus on implementing your gameplay. (DO NOT fall into the pit of polishing it or ADDING NEW features).

Either way write a throughline/goal for your project (what you want to tell or achieve with your project) and prototype(draw it on paper first) a core gameplay loop that you think is fun and one that validates your goals. (Choose from an idea that excites you)

Then test it (however you can) and iterate based on your own input or others input.

And importantly DO IT, make whatever little shitty prototype you think of and share it with people! Get their feedback!! Your prototype will suck so hard in the beginning! (Mostly) But the feedback you get will help you make it awesome!

I can't help with making it stress free, I myself struggle with that. Just do it for fun, I suppose. If you start thinking about how to make money off of it or how it will revolutionize the world, then you'll never get to making the damn thing.

Hope this helps.

Edit:

Okay, so it just struck me. I think you have to focus on what excites you, because if the idea doesn't excite you, you are going to have a lot of trouble expanding upon it. It will also make it less stressful. So keep that in mind.

Edit 2:

A good way to build ideas is to copy others. See what you liked about someone else's game and think about how you would improve upon it in a way that would interest YOU. This way you have some boilerplate and an example to help guide you.