Challenge: design a world that has no generic terrain whatsoever. No deserts, no forests, no swamps per se.
Sure, you can start with "desert" or "forest" as a descriptor, but run through some questions to inspire you to make each region unique.
Is there an unusual form of precipitation? Does it rain dust, or ashes, or weak acid, or salt water?
What are the agents of erosion? flash floods, giant vermin, ghosts, an everburning wildfire, warring giants, earth elementals?
How do you find water? Lick it off of fuzzy plants that capture fog? Look inside the cistern-like interior of giant conifers? Collect it from boiling springs? Place a water bottle beneath the ever-weeping eyes of the stone statues that dot the landscape?
What are the largest natural landforms and structures here? Basalt columns? Sinkholes? Petrified trees? Skeletal corpses of dead angels? Rafts of vegetation floating on a foul, muddy sea?
What adaptations have local humanoids made to survive here? Do they live underground? In tree canopies? Do they drift along beneath clusters of air-dwelling puffer fish? Do they spend their days as animals and shift into human forms at night?
Where does the past still intrude on the landscape? Colossal statues carved from sandstone mesas? Mysterious straight-as-an-arrow roads made of quartz? Piles of charred skulls? Abandoned fortresses whose walls are carved with protective magic spells? Thousands of crudely made statuettes half-buried in the earth, each with an iron pin through its heart?
What are the ubiquitous nuisances? Occasional sounds of disembodied laughter? Dust golems spun from residual magic? Storks that collect shiny objects? Innocuous mummies that only want to recite the laws of the land to any strangers who happen by?
Who are the low-level humanoids here? Bandits who ride on vultures? Hermits who live inside sanctuaries made of living vermin? Hunters who can kill their prey with song?
What are the unique resources? Geodes that contain magic spells? Parasitic crystals that grow on the skins and hides of local herd animals? Trees that can be shaped by thought?
Hope this kickstarts your sense of wonder.