I was greatly saddened by Dev Update #29. I am a retired Systems Engineer / Lead Programmer and I have heard this same story for years and it seems our education and mentoring systems are doing very little to address the problems. When there is a rush to produce untestable code in the hope of meeting a release date you end up in the situation you are in. Fragile software where people are afraid to change things because it breaks other things. Education systems should be teaching techniques like TDD (Test Driven Design) along with design techniques like (MVP) Model View Presenter or (MVC) Model view Controller. When these are followed no code is added unless there is a test that demands it. Most team don't do this because they are afraid it takes too much time but actually it saves time in the long run by reducing the time it takes to find and kill bugs or fear adding new features because it may break things. Another design technique to be followed is to ensure Migratable data. So when you add new features you don't have to wipe out old save data and can just migrate it to the new format.
It seems you have a talented team there based on how fun the game is. It just saddens me they have never been mentored in techniques that help both them and the software be better and less fragile.