Fly with nostalgia is a mod adding a retro flight mode, similar to the pre-creative days of Minecraft. Players with the retro flight mode active can walk through the air on glass platforms which slowly disappear behind them.

Enables or disables retro flight mode for the player. All the arguments are optional.
Command format: /fly <targets> <radius> <enable>
targets - choose one or more players for whom the retro flight mode will be toggled.
radius - set how big the platform should be (in blocks around the player). Defaults to 3.
enable - specify if the flight should be enabled (true) or disabled (false).