From the very beginning, director Masahiro Sakurai had a bold vision for Super Smash Bros. Ultimate: he wanted the game to include every single character from the series’s long history. It would mean a lot of work, covering everything from negotiating for the rights to the likes of Mega Man and Metal Gear’s Solid Snake to updating the graphics so that older characters didn’t look out of place. Ever the perfectionist, Sakurai also wanted to adjust each fighter in an attempt to speed up the game. When he explained this undertaking to his team, he was met first with gasps of surprise, followed by quiet, as the developers realized the task ahead of them. “From where I stood, all I heard was dead silence,” Sakurai says.

The reason for their surprise is clear when you understand how the new game will work. Super Smash Bros. Ultimate launches on the Nintendo Switch in December, and when it comes out it, will be the most comprehensive version of Smash to date. Its cast of characters totals more than 60 fighters — including new additions like Ridley from Metroid and the Splatoon inklings — each of which has been meticulously tweaked and updated to fit in the new game. Characters like Link and Mario have new looks to match their most recent adventures; Link sports a Breath of the Wild outfit, for instance, while Mario is now accompanied by his Super Mario Odyssey sidekick Cappy. Sakurai knew it would be a challenge when he took on this goal, and his suspicion was proved right. “I speak from the depths of my heart when I say it’s a lot of work,” he explains.

The director is somewhat infamous for his workaholic nature. During the development of Super Smash Bros. for the Wii U and 3DS, he penned a column for Japanese gaming magazine Famitsu outlining just how strenuous directing a new Smash Bros. can be. “I work from mornings to late nights, even on weekends and holidays,” he wrote back in 2014. “I hardly have any free time, let alone time to play other games.” He added that “developing Smash Bros. is beyond hard.” Though he was the director on the game, Sakurai was still involved in the finer details, constantly inputting data to adjust the parameters of each fighter, making sure they move and fight in just the right way.

For Ultimate, he no longer has to do all of that, but that doesn’t mean his load has lightened. In fact, he says that because of the huge roster of characters, his “workload is still pretty much the same.” That said, Sakurai was persuaded that it was possible to make such a big game for two main reasons. The first is the team he’s working with: for the Wii U version of Smash, Sakurai’s studio Sora partnered with Bandai Namco to develop the game, and it’ll be largely the same staff working on Ultimate. That continuity helps smooth out development, as do the relative technological similarities between the Wii U and the Switch, which made moving over many of the characters to the new game a much simpler process than it could’ve been.

The ultimate goal is not just to create the most comprehensive version of the beloved character fighter but also one that speaks to its two very different audiences equally. Smash Bros. has a dedicated competitive scene where hardcore players are very cognizant — and vocal — about even seemingly minor changes to the experience and the balance between the overall roster. But it’s also one of Nintendo’s tentpole releases, a best-seller that sits alongside Zelda and Mario Kart. According to Sakurai, seeking out that balance is part of the reason he’s stuck with the franchise since its inception, despite all of the long hours involved.

“I don’t think I’ve ever made something that I’m totally satisfied with,” he says. “That feeling of doubt, or wanting to do more, is my engine to move forward and make the next iteration.”