Very cool. In 1998 (oof) we built Road Rash 64 which was accidentally open world -- even though you had race on a particular road, with a start and finish line, you could drive anywhere, see traffic all over the map, jump off of mountains, etc. The r4k plus reality coprocessor was quite potent -- we got to over 750k shaded triangles per second in optimized testing -- though finicky because you had to manage audio during vblank, etc. Plus, the reality coprocessor fog had a brutal hardware bug that made it really tricky to use.