Igualada River is a conceptual level/art piece made in Unreal Engine 4. It is loosely based on a real-life cemetery in Spain designed by Enric Miralles, whose floorplan is intended to mimic a river's path.
I took this metaphor and applied it to a linear design, where the player starts at the bottom of a hill and weaves upwards until they reach a structure at the top. During the climb, the player encounter five obsidian graves, each of which holds a stone face. Each stone face is less decrepit and destroyed than the last.
During the climb, the player is intentionally denied any opportunities to look up or down the mountain--they can only barely see their final goal. This denial creates a sense of seclusion, contrasting strongly with the flat, open-air architecture of the buildings themselves. This subtle tension builds as the player climbs towards the top of the mountain and the level grows more claustrophobic, finally resolving at the very end when the player stands at the top and looks over everything they have traversed
When development started, one of the first decisions I made was to abandon any nonlinearity in the original cemetery and fix the level's emotional arc to a straight line. Since only one player would be navigating the space instead of many, using the river as a metaphor for specifically the player's life instead of a broader allegory for anyone's life made more sense for a contained experience. At this point I was still imagining my level as a cemetery, but having graves along the path of the player's personal life journey didn't really make sense conceptually, so I got rid of those as well. I replaced them with five grave-like structures that stand for the player character's emotional journey.