In their GDC talk "Making A Sequel To A Game That Doesn't Need One," Portal 2 writers Erik Wolpaw and Chet Faliszek detailed a very different version of one of the most beloved games of this generation. Early in development, Portal 2 shared little in common with the original outside of the title and the involvement of Aperture Science.

Originally, the game was set in the 1980s. Players would wake up on what appeared to be a desert island, complete with palm trees, hammocks, and a beautiful view of the sea. Upon attempting to explore, however, the player would be stopped by glass walls that eventually enclosed them on all sides. Your protagonist would watch helplessly as the trees sink into the ground, the water level recedes, and the environment reveals itself as yet another Aperture test chamber.

Eventually, players would discover that they were playing as a different character this time around. This protagonist went by the name Mel, and featured a different colored jumpsuit than the first game's Chell. Wolpaw explained, "Honestly, we felt as writers that she had her day. She fought GLADoS, escaped, and we just let her be."

When they took this version to QA, they found that testers didn't immediately mind the change. However, they eventually became disappointed when GLaDOS woke up and didn't recognize the player as the character that defeated her in the first game.

Before that build was complete, Chell wasn't the only character absent from Portal 2. GLaDOS wasn't a part of the game's original plan, and Cave Johnson was set to be the primary antagonist. He would talk about every test chamber as the player entered it, and this would be followed by the appearance of a small robot named Betty. This droid would roll into the room and quickly spout legalese, similar to the side effect disclaimers during prescription drug commercials.

Players had a glimpse of different personality spheres late in the final version of Portal 2, but the original plan called for numerous spheres outside of the bumbling Wheatley. One was referred to as the "Morgan Freeman sphere," and it possessed extraordinary wisdom...although his knowledge was confined to information about the 20x20 chamber he lived in.

While the game was always going to be called Portal 2, the first drafts omitted the titular gameplay mechanic entirely. In its place was something called the F-Stop, which Wolpaw and Faliszek declined to comment on. Interestingly, they explained that they didn't want to talk about it in case they wanted to use it in the future.

If you played Portal 2, its insane ending is most likely still fresh in your mind. It was a universally beloved conclusion to the game, but it wasn't always the only one. The team at Valve originally planned on including numerous false endings throughout the single-player story. In the first game, some testers were tricked into thinking that the slow ride into the fire pit was the actual ending of the game. "A small percentage was fine with just riding it into the fire. That was a good ending for them," says Wolpaw.

Encouraged by the response to the original's false ending, the team planned on repeating this joke, along with a new song each time. The first would occur only two minutes into the game, and ended with a song sang by Wolpaw and writer Jay Pinkerton that recapped the thrilling events of those initial 120 seconds. Another would have been triggered at a point where the moon was visible through a crack in the ceiling. If the player shot one portal on the moon and one on the wall, they'd be sucked into space. The game would "end" with Chell asphyxiating in space while listening to a sad song about the moon. Eventually, this concept was altered until it became the actual ending for Portal 2. "We managed to make it a great mix between totally awesome and completely stupid," said Wolpaw.

Also in place during Portal 2's early days was a competitive multiplayer mode. "It was a mix of the Amiga game Speedball and Portal, but with neither of the good parts of either of those games," says Wolpaw. The mode was scrapped quickly, but some of its concepts made their way into the eventual co-op mode.

Near the end of the talk, the writers opened up to questions from the floor. One attendee asked if we'd ever see another Portal game, considering the first game never needed a sequel to begin with. Wolpaw and Faliszek didn't say anything, and responded with some brief, nervous-sounding mutters. It obviously wasn't any kind of confirmation, but in combination with their thoughts on further utilizing the F-Stop mechanic, some Valve fans may take it as a hint towards the continuation of the beloved series.