My game dev process starts with a text outline of my ideas, usually including some sort of pseudo code. I use Obsidian's canvas feature to write things out and organize.
Then I make a demo project in a game engine, and do my best to create said feature or mechanic.
You can, also, use blender to outline how exactly you want things to look. If it's very visually specific, you can animate it and then in your engine of choice, use root motion so it looks 1:1 the same in blender.