Downfall is a cancelled unfinished special map for Slendercraft.
Downfall is a map with a unique design and play style. The map is designed to look unfinished on purpose, and its all one floating platform so high in the air, that its an instant death if you fall.
The map's production was halted for about a month until Shadow Realm was revealed. When this happened, Shadow Realm was confirmed to be the reworked version of Downfall.