Modern engines render scenes in multiple passes, iterating over the same framebuffer until everything has been rendered. Engineering such a flaw in a way that w

Modern engines render scenes in multiple passes, iterating over the same framebuffer until everything has been rendered. Engineering such a flaw in a way that wouldn't lead to dramatic cascading effect will indeed be very difficult to design. Note that sometimes games do need absolutely exact results, or at the very least reproducible results. For instance sometimes you want to use something like `glDepthFunc(GL_LEQUAL)` which will only accept a fragment if its depth is equal to the depth buffer's value. A small fudging here would cause potentially large visual issues. I'm not saying it's impossible but I expect that it would create a lot of headache as random, potentially unmaintained games would start glitching here and there.