Give a bit more context on what you are already using so we are not shooting in the dark. You are likely already using these: With a typed language the compil

Give a bit more context on what you are already using so we are not shooting in the dark. You are likely already using these: With a typed language the compiler helps you refactor more efficiently. No spaghetti code, instead move logic into coherent (ideally functional) libraries. I’ve found the functional object-oriented style to give most flexibility for changes. (Ie. Animal.kill() doesn’t modify it but returns a new Animal object.) Copy-on-write everything, use appropriate data structures to make it efficient.