Welcome Back is an alternate ending to Portal 2, based off the thought "what if those four singing turrets did shoot?" With new characters, more mind-blowing puzzles, and new bts areas, this mod will be an experience you'll remember for a long time.
Here you go, the official trailer for Welcome Back. Sorry for any transitions between footage that don't make sense, Windows Live Movie Maker wasn't the greatest at this.
Song: "You will be perfect" from the Portal 2 official soundtrack by Valve.