Rio was our initial prototype level for Rigs (2016). It went through a huge amount of iteration and experimentation and probably if we were to start it again at the end of the project we would have tackled a lot of it quite differently.
One of the areas we found that definitely worked was the strong colour coding of zones, we established a visual language on Rio that we would have a red end and a blue end for each team, and then we would have a central yellow area to signify you were close to the powerslam goal. Another area we found that was effective on Rio was to have a detailed surround that gave a sense of scale, the city itself had a fairly bumpy development but we pulled it together in the end.
Lighting wise Rio was always intended to be about bright vibrant colours. This is something that needed a lot of fine balancing to not overwhelm the player. Bounce light from the strongly coloured surfaces was very important.