If you're going to have terrain detail at all, you should think about the atmosphere first. No atmosphere is transparent. Earth's atmosphere is thin and transparent enough that you can
see terrain through it, but a lot of detail is lost, and there are clouds to complicate matters. On Venus, it's always cloudy and though there is a rocky surface, you can't see it from space.
The atmosphere will reduce the amount of detail you can see to the major, large features. Deserts, wooded areas, snowy areas, etc will all show up, mostly melding softly into each other, even though in reality the transitions are closer to being stippled, the alternations don't show up at that scale. Dithering is appropriate to use since it's also basically stippling that looks like a smooth transition. Vertical features are usually too small relative to the size of the planet to be visible, so it's all about large-scale horizontal features. Even Mars's Valles Marineris has very little discernible depth when seen from space.
Think about the scale. How big does a feature have to be to be 1px wide? You drew beaches on some of the shores, but if that's an earth-line planet, then that means 1px of beach is over 100miles wide!
By the way, your game looks very dark. I have to squint to make out the details. Even the lander is hard to make out. Space, because there's no atmosphere getting in the way, can actually be quite bright, especially near planets that are close enough to stars to have what looks like liquid water.
