Why would you assume that? That's not even true of regular software :D But also, as long as the game works on the specific hardware it was designed for then th

Why would you assume that? That's not even true of regular software :D But also, as long as the game works on the specific hardware it was designed for then that's all that mattered, which was my point. If it reads uninitialized memory or depends on exact cycle counts or some undocumented hardware behavior then that's _fine_ if it still works on the real hardware, plenty of that was even intentionally done to achieve things otherwise impossible on that hardware. At the same time it makes it almost impossible to verify even trivial changes to a function. Once you start accounting for all the potential state differences the answer to "does this function work the same?" will basically always be 'no' unless the code is identical. The only way to eliminate various kinds of state from being a concern is to analyze where the function is _used_, rather than just the function itself, and that's an entirely different and much harder kind of challenge.