I'll begin with an extreeeme example, in the worst possible case: Imagine that a S3k cartridge has a slight ROM corruption in such a place you wouldn't notice at first glance, while the game apparently plays fine. At Sky Sanctuary Zone, an average player transforms into Hyper Sonic at the same time an Eggrobo is zooming into the screen. I don't know specifics, but according to a video made by Orkal, doing this causes such a VRAM clash, that either this badnik or the surrounding stars mess up. When that happens, the player says "uh, I have just glitched the game, dem programmers". Later, the player beats the zone, and when Death Egg Zone begins, the whole tileset appears like a broken mess!!, but, because he glitched some sprites earlier, to him it will look like this is a similar issue again. However, there's no known bug that affects the tileset loading, so chances are it's fault from the tileset itself being corrupt instead. How will the player know the difference? This community has proven me that every single thing, is questionable. Thinking in Murphy's Law, checking the checksum is useful to ensure the ROM's integrity, in case the file's download has been corrupted or the flashcart didn't flash the file correctly and doesn't do any integrity checks afterwards. The idea is to avoid the scenario from above. Then if the check is seriously THAT annoying for some, it could skip any subsequent checks with a flag on SRAM. Earlier, I was randomly looking for opinions on a checksum check routine I wrote. However.. the answer? That it's all useless, and at any cost that I should drop it. The reasons, in case of any issues, "the fault should lie with the person flashing the rom not the hacker of the game except for when said hackers make the hack buggy", "they complain then you tell them to reflash it", "for data integrity checksum is bullshit - an LFSR is much better (to not go into complicated stuff like SHA or CRCs)" and most importantly, that flashcarts are stable enough, even though someone else claims it failed once. Personally, I don't think it's fair to get reports of bugs that haven't been our/mine fault, nor waste time on something I can avoid, with ease. What's your opinion on the matter, though?