In a recent essay written for An-An magazine, Kojima comments, "It was 1986 when I entered the game industry. Games still couldn't speak. Characters did not have voices. Kanji fonts weren't supported, and you could only show one katakana character at a time. Solid Snake, the protagonist of my debut title Metal Gear (1987), was born as a silent 'tough guy' because of these circumstances."
Metal Gear was originally released for the MSX2 home computer. Memory constraints made it impossible to display kanji, so the game was written entirely in katakana, Japan's simpler phonetic script. Obviously, voiced lines were out of the question too, and Kojima suggests that these limitations contributed to him choosing a stoic and silent protagonist for the game.
On the other hand, with 1998's Metal Gear Solid, Snake got his voice. "Now, the silent Snake could speak, delivering snappy lines reminiscent of 007 or Lupin the Third," Kojima comments. Although he debuted as an essentially mute character, a big part of Snake's popularity came from the performances of voice actors like Akio Otsuka and David Hayter.
But despite technological advancements allowing Snake to deliver his "snappy lines" (and have a voice in the first place) his silent nature remained important for his fundamental role in the Metal Gear series. Commenting on Snake's very palpable lack of dialogue in 2015's Metal Gear Solid V: The Phantom Pain, Kojima told IGN that "Snake is and always has been nothing more than an extension of the player. He's your alter ego. Therefore, I made a very conscious effort this time to bring Snake closer to the player's perspective." These efforts included limiting spontaneous comments from Snake and making him, essentially, a silent protagonist (Kojima compares him to Mad Max in Mad Max 2).
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