Experiment 427

Experiment 427 is a free modification for The Stanley Parable. During development, the modification got abandoned and never got finished. There is a beta version, however.
The mod begins when a player activates the Confusion Ending and clicks on the Confusion Schedule. The player is then teleported out of the map on the opposite side of the Confusion Schedule and begins a new adventure. The mod was also going to customize the game's textures, add new objects, change the main plot, and add new rooms.