Making the challenges more visual and a lot less text-based – that was not a controversial [approach]. Ernie was saying the same thing – he was pitching stuff to me before I even came up with stuff myself. You always figure, if the author of the book is telling you, please change this, then you have licence to change it.

What you’ve done with Halliday’s really interesting. He becomes a quite immediate character in the film, I thought, and slightly melancholy, too – a lot of the games he creates for the players are more obviously rooted in his regrets.

Yeah, definitely. And look, I pushed in that direction, but so did Steven, and there’s a lot of Steven’s relationships with his own friends that Ernie was calling on anyway. But I think through the actor and the director and so many other people, the part evolved. As a writer, you have to give them a pathway. I said in the first draft, this has got to be about Halliday – and some of this is in the book, by the way, just in a different order – but it’s got to be about Halliday confronting what he did wrong.

It can’t just be, he didn’t kiss a girl. That’s not enough. It’s fine that he thinks that’s what he did wrong, but that can’t be the deeper meaning there. There’s gotta be some insight that Halliday gained that he’s trying to impart – that’s what really does set him apart from Willy Wonka – this is a guy who’s already dead, who’s trying to find someone to take over for him, and he’s a game builder. So I tried to take all that and say, okay, well how is this not a bad idea?

That was one of the things that was helpful about it. The scene where Sorento points out, “This is a terrible idea” – he has this huge company that’s super-important to a lot of people, and he’s created a game to figure out who to run it next. So I tried to go from that and make Sorento right in his own mind, but then have the contest also be something that says, no, a lot more thought went into this, and Halliday had a lot more regrets than he let on. That was a really helpful way to look at it for me.