Sonic the Hedgehog's creator had "never seen anything like it in a video game" before he designed it.
Tom Kalinske, former head of toy company Mattel, recalls how he couldn't believe how quickly the character was able to move across the screen in the early 1990s when it was first created.
He said: "The character moved very, very quickly across the screen. I'd never seen anything like that in a video game before."
And Kalinske can't believe how well the Sonic character has done.
He added: "From day one, once we saw that Sonic was the character we were going with I wanted to have a television show and we ended up actually having two different ones. It was really frankly an amazing accomplishment."
Sonic is now regularly spotted alongside Mario in a number of games and whilst Kalinske admits he never thought he'd see the two characters in the same game after Nintendo and Sega took on one another in the 90s.
Speaking to BBC Newsbeat, he explained: "I mean, obviously Nintendo is [one of the] top dogs and so Sega not doing hardware anymore, they have to be cooperating with the big manufacturers."
