Here's one of the Ringworlds we're planning on putting into Dominion if it gets off the ground!
I've covered this in my Journal, but thought it worth a shot at IotD ;)
This Ringworld gives roughly 186,000 times the surface area of Earth - so represents a substantial texturing challenge! At the moment its a tiled planet surface as R & D, but the final beast will have a constantly changing surface all the way around - perturbed from a seeded "starter" texture.
The scene above shows the cloud layer, and the shadows evident on the surface of the Ring itself. Right now there is no "night" - the entire Ringworld is lit 24x7. Larry Niven's Ringworld had a solution for this (shadow panels closer to the star) but I'm thinking along different lines - yet to be confirmed.
It also shows a space-station orbiting above the Ring surface - the primary point for interacting with the Ring's inhabitants in Episode 1. The station is a placeholder - being a pre-bought model available on Turbosquid.
Solar radiation will be buffered away from the Ring surface by a vast force-field - which also contains the atmosphere inside. Solar energy is diverted around the Ring itself and then collected by energy harvesters along the dark-side to be used to power the huge force-field arrays, amongst other things.
You can fly to any point on the Ringworld - it's not a baked scene, it's a physical construct existing to scale in the game-engine. Flying above the surface is something to be seen ;) But for now I've left it as a special "Backer" treat on my kickstarter project page.