I'm pulling apart and rewriting so far a little in C a personal fork of OpenTTD 12.2. I began on it a few years ago for the first time for the heck of it after patching for realtime, began again while adding features I wanted until I hit a bad enough snag, and now began again by first extracting most used functions and profiling with Valgrind inbetween.

Things I noticed are inconsistent coding styles, overly complex processes, unused(!) functions, inefficient data use, nothing surprising with a project worked on by various people in their spare time and their own ideas on how to code. And this isn't even talking about later versions. To me it's an example of how unrestricted access to bling features causes a mess.

Eventually I want it converted to C (C23), split apart in seperate functions with a decent source code organisation, and simplified processes to make it easier to understand what's going on and extend fuctionality. For this I need it simplified as possible and weed out the layer of complexity caused by C++ first. Going to take plenty of time, but I'm still having fun doing it (most of the time anyway :-p ).

I'm not advocating anything, but it's satifying to me to bring clarity to code and see small improvements to performance during the process at the same time. It also gave me an opportunity to develop a unique syntax style that visualises parts of the code better for me.