Nostalgia Run is an interactive floor consisting of 4 stages on which you need to pass obby. If you fall on this floor, you will be teleported back to the elevator.
Stage 1 looks like a lake with small stones and water lilies, which you need to jump on to enter the tunnel and get to stage 2. Stage 2 and stage 3 are a small cave with stones that you need to jump through to get to stage 4. Before stage 4, you get into a black tunnel, where you you need to choose one of the ways. 1 path consists of multicolored slabs that constantly change their color, along which you need to jump to reach the end of the obby, 2 path is about the same, only the walls remain black, and the slabs are not repainted.
Intresting facts:
At stage 2, you can see G_XAR in the corner, which you can get to if you turn around and jump on a stone before exiting
This floor reminds many players of the floor from The Normal Elevator - Speed Run
On this floor, at stage 1, there are 3 stones to the right of the elevator, if you jump through which you can get into a secret tunnel where there are several boxes and a boarded-up passage with 4 elevators from The Normal Elevator inside. This is probably a reference to the same tunnel in The Normal Elevator.
This floor was more complicated before the balance update