I run into this a lot. I have started writing multiple Main classes, and point gradle to the one I am working on. So when I work on trees, I make a new main that only shows trees so I can get them right, then migrate that code over to the RunGame main class, or an appState.
Also, only attach the appStates I need to speed up the run time.
Now, I have gone so far as to rip out each part into it’s own project, and importing them to the main.
And finally, a quick GUI that can change numeric values will make dev a billion times faster.
And finally finally, it looks great, some AO will help make the grass pop