memes

Water doesn't have to be the thing that brings variation. Titan has a methane "hydrology" with clouds, rivers, valleys, and beaches whose sand is made of ice. On Triton, ammonia cryovulcanism powered by tidal forces from Neptune create plains with ammonnia snowfall, ice mountain ranges, and underground lakes. On Miranda, the planet is ice, but there are massive terrain differences from 10 km cliffs to flatlands. Io has a massive variety of volcanic planes with color differences visible from space because of their entirely different chemical compositions. The turbulent atmosphere of Jupiter is streaks of water vapor clouds, upwellings from deep beneath the surface, cyclones and massive pressure drops that dent the atmosphere inward by kilometers, with ionosphere above and gas as dense as water below. Even an atmosphere-less grey rock like Mercury has basalt plains, craters, ridges, highlands and dust plains.

In No Man's Sky, many planets have life, which requires complex chemistry being possible at the temperatures the planet has using the chemicals that are available on that planet. This then naturally creates temperatures that are "too cold" for that life and "too warm" for that life, and complex adaptations made by that life to take resources from places that get "too cold" or "too warm" with less risk of predation or competition. Similar adaptation is possible to other extremes/variations, such as "submerged", "on land", "flying", "too dry", "too few nutrients", "too acidic", "too basic", "too steep", "cave", etc. And thus we get complex biospheres that vary across the planet.