[vhxijamh] Infinite open world

In an open-world game, instead of running into an impenetrable barrier at the edge of the world, let the world go on forever, just full of boringness to discourage (but not prevent) players from going beyond the edge the interesting play area.

Coordinates need to be arbitrary precision integers or fixed-point reals with arbitrarily large magnitude.

Inspired by Zelda BOTW.  Fairly easy and natural would have been endless desert, endless ocean, endless snowfield, and endless lava lake in some of the out-of-bounds directions.