A lot of floppy-based games have on-disk copy protection patterns that take advantage of undocumented behavior of disk drives at the time. So much so that tools like Greaseweazle [0] are necessary to compose full magnetic flux maps of archived floppies.

Another thing is that these games are often made to run on a wide variety of graphics and sound hardware, and effectively have drivers compiled into them.

[0] https://github.com/keirf/greaseweazle