Fans of Portal are almost certainly familiar with GLaDOS, a maniacal robot that has become something of a video game icon. While GLaDOS is a key character in the Portal franchise and an all-around noteworthy villain, it turns out that the character was a last-minute addition, and for something of a funny reason to boot.

In an interview with TechRadar, Valve's Robin Walker discussed a bit of the history behind the antagonist. As it turns out. GLaDOS wasn't originally going to be in the game, but was added towards the end of development because of playtesters. Essentially, playtesters weren't certain when the game was going to "start," many believing that they were part of some drawn-out tutorial. Of course, that was a problem for the development team to solve.

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The team came to realize that Portal needed some sort of threat to motivate players, otherwise, the game simply wouldn't be any fun. According to Walker, that situation spawned the idea for what would eventually become GLaDOS. "There needs to be some threat, some force, something that makes it look like it's going to push back. That maybe there needs to be some concept of what failure can be for the gamer," Walker said.

Walker went on to make a number of great points about the relationship developers have with games versus the relationship players have with games. According to Walker, developers tend to respond to mechanics more than anything, but players need something with emotional impact to get hooked on. Walker also acknowledges that these aren't hard rules, citing Tetris as an example of a game without an antagonist, but the point still makes a lot of sense, especially with modern games.

Those that have played Portal will likely agree that GLaDOS fills that gap well, so it's good knowing that everything shook out for the best. It may seem strange that such a key element to the franchise took so long to come to fruition, especially given the impact that GLaDOS has had on the games industry ever since. In many ways, GLaDOS helped define an entire generation of humorous villains, and it's difficult to imagine Portal without them.

It's interesting to consider what would've happened if Portal had shipped without GLaDOS. There's a good chance that it would've never had the impact that it did, which would've been a significant butterfly effect considering how many games Portal has influenced. Luckily, fans don't have to worry about that possibility, as the present is now secure. Of course, players are still hungry for Portal 3, though whether or not they'll get that is a mystery.

Portal is available now on PC.

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Source: TechRadar