One of this year’s biggest gaming surprises was how well the Super Smash Bros. Ultimate roster expanded. Along with Joker from the Persona series, Terry Bogard from Fatal Fury, and Banjo-Kazooie, fans also got Hero from Dragon Quest XI in a number of variations. But a new interview indicates that it wasn’t always easy making them fit into this fighting world.

In the latest issue of Nintendo Dream, Dragon Quest XI producer Hokuto Okamoto explained how hard it is to fit characters from the saga in any other type of game. “I was quite surprised when I first heard about Super Smash Bros. Ultimate,” he said. “It’s nearly impossible for Dragon Quest characters to appear in other companies’ games. We discussed many ideas, including what we’re doing with DQXI S, such as making each color a hero of past games.”

But, fortunately, it all panned out in the end. “Mr. Sakurai [director of Ultimate] accepted both Nintendo’s direction as well as Square Enix branding, and then got on board. It was a very exciting experience.”

Director Takeshi Uchikawa also noted how he was “impressed with the map being very dynamic” for the game. “It fully incorporated various series staples, such as the command selection,” he said.

Development director Masato Yagi had input as well, particularly with how the characters were utilized in the game. “The things people are doing with Hero is impressive,” he said. “I’ve considered how to turn a Dragon Quest battle into an action game, but I think this was an amazing opportunity.”

Uchikawa added, “It’s spectacular what Mr. Sakurai can find to include.”

The additional DLC has certainly paid off for Super Smash Bros. Ultimate. It recently became the best-selling fighting game ever, clearing 15.71 million before the holiday season. With a fifth fighter still to come sometime in early 2020—and a new season introducing even more fighters to the fray—its popularity is sure to keep going.