As the source code has grown and also the scope of the project it looks like all I have to do is solve puzzles. They are unfinished features or some part of source code I've marked.
These days I try to find some kind of quick solution to these puzzles, just to get somewhere. It's also tempting to simply remove the feature for now, but then you go back to simpler gameplay and finally reach a game that has complexity of a 7DRL. All that in 30 years of development.