I think the very best thing one can do is reduce the amount of variation you have to support. The burden of change is thus vastly reduced and the number of poss

I think the very best thing one can do is reduce the amount of variation you have to support. The burden of change is thus vastly reduced and the number of possible avenues for improvement explodes. We could have left customers with old operating systems on the older versions of the product. A lot of them never upgraded anyhow. We absolutely destroyed our productivity by not making this kind of decision. We also really hurt ourselves by supporting Windows - as soon as there are 2 or more completely different compilers things turn to **t. I'm not even sure we made much money from it. Given the ability to use new tools (clang, gcc and others) that are only available on newer operating systems we could have done amazing things. All those address sanitizers etc would have been wonderful and I would like to have done some automated refactoring which I know clang has tools for. Most of the problems were just with understanding the minds of the developers - they were doing something difficult and at a level of complexity that somewhat overmatched the problem most of the time but the complexity was there to handle the edge cases. I wanted to go around adding comments to the files and classes as I understood bits of it. I was working with one of the original developers who was of course not at all interested in anyone understanding it or making it clearer and this kind of effort tended to get shot down. If you don't have good tests you're dead in the water. I have twice inherited python projects without tests at all and those were a complete nightmare until I added some. One was a long running build process in which unit tests were only partially helpful. Until I came up with a fake android source tree that could build in under a minute I was extremely handicapped. Once I had that everything started to get much better. My favorite game ... is an open source C++ thing called warzone2100 - no tests. It's not easy to make changes with confidence. I imagine to myself that one day my contribution will be to add some. The problem is that I cannot imagine the current developers taking all that kindly to it. Some people get to competence in a codebase and leave it at that.