Of all the games of E3 2017, Mario + Rabbids: Kingdom Battle stands out as the biggest surprise - even if we all knew about it beforehand. After its existence leaked towards the end of May, enthusiasm towards it was low, and then... Ubisoft's press conference began. Company president and figurehead Yves Guillemot stepped out on stage to introduce the game, and with it, a very special guest. Shigeru Miyamoto and Yves Guillemot.

What happened next - the arrival of Nintendo legend Shigeru Miyamoto and the two CEOs posing with oversized props - will go down as the start of E3 2017's best press conference, and one of Ubisoft's strongest showings of all time.

The duo exuded a sense of fun and positivity found lacking from other shows. Everybody fell in love with the game's tearful creative director Davide Soliani, overcome with emotion in the audience. Oh, and Mario + Rabbids itself? Its deep, turn-based tactical gameplay has silenced critics.

Two days on from Ubisoft's press conference, and I'm sat much closer to both its stars. Across a table upstairs in Ubisoft's E3 booth, ringed by almost a dozen PRs from the two companies, is Miyamoto himself, with Guillemot beside him. I'm here primarily to discuss the development of this special project - but also some other topics besides.

(If you missed it yesterday, we snuck in a quick question regarding the status of Miyamoto's long-awaited Pikmin 4 project, which he was kind enough to update us on.)

How did Mario + Rabbids come about, and why now? It feels like the product of a very special relationship between your companies.

Shigeru Miyamoto: It started out when launching Just Dance in Japan - and the idea to have Mario in there. Ubisoft has provided a lot of support for [Nintendo] hardware and they understand how it works. They've made products which are very satisfactory and fit the market we're shooting for. We've had a relationship now for over 20 years, but this is the first time we're operating at the level where we're sharing characters.

In terms of major games in both companies - Ubisoft has Rayman, it's a similar sort of platformer. We thought about ways of collaboration and then Rabbids came up - and that them collaborating with Mario might be a fun idea. We also wanted to create a new genre with this collaboration.

Yves Guillemot: We admire what Nintendo does. We also thought we could learn a lot from this collaboration. Our teams did Just Dance together - Nintendo published Just Dance in Japan, and they reworked the core concept to make it fit with the Japanese market.

Xavier [Poix, Ubisoft's French studios manager] and his team made a proposal to Nintendo to put those two worlds together, and Mr. Miyamoto reacted strongly - three years ago actually, at E3 - saying 'I'm ready to see more'. So Xavier's team went to Japan to show more of that possible collaboration.

What were the conversations like behind the scenes, feeling out what each set of characters could or couldn't do - I know you're both obviously protective of your respective IP. Some people were surprised to see Mario shooting an energy gun, for example.

Shigeru Miyamoto: In terms of Mario wielding a gun, it's something which was talked about for a while within Nintendo to work out what the appropriate way to do that would be. There was a time in the development of Splatoon where it could have been a Mario-based game. But we decided that a new style of weapon would work. We had a lot of discussion between Ubisoft and Nintendo to make what you see today.

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What's next for the Nintendo and Ubisoft partnership - do you have plans for more collaboration in the future?

Yves Guillemot: It's too early to say - we're finishing the game and we'll see what it does. For sure, we'll analyse if we can do other things, but the first step is to make sure this one is coming along well. And there will be some extra content coming along after... It's already a long-term partnership on this one.

Great to hear. With Mario + Rabbids, the internet already had a fair idea the game would be announced - and, with the greatest respect, Ubisoft is known for its games regularly popping up online before they're meant to. What's happening here? And can you shut down the conspiracy theories Ubisoft is behind any of the leaks itself?

Yves Guillemot: First, I want to reassure you - we are not part of that [laughs]. We combat it, because we think it's not a good way to present a game. What we're happy with is a few games were still not known by the public [at E3] so you could discover Beyond Good & Evil 2 and the others. It's good we are managing to still keep... some secrets.

I admit, I got a little emotional at that BG&E2 reveal - I have waited so very long for that game. To see it being committed to publicly again was fantastic.

Yves Guillemot: You liked the presentation?

I did - I thought you guys had the strongest of all the live press conferences. I think many people online would agree too.

Yves Guillemot: Nintendo was very impressive as well - but [looking at Miyamoto] we had a star on stage.

Your moment on-stage together really began this week's swell of enthusiasm for Mario + Rabbids. And also provided for a lot of GIFs.

Shigeru Miyamoto: I enjoyed it very much too.

Finally, Mario + Rabbids feels like a game which reflects some of the playful, individual nature of both your companies - and for Ubisoft, it comes at a time where there is a genuine threat to the company's independence. Is it important to show projects like this now?

Yves Guillemot: Yes it is - it's important to show what our teams can do. What is important - and always has been within the company - is to create something new and different. Here, [our developers] were so happy with the potential collaboration with Mr. Miyamoto, to learn from the master of this industry, to collaborate with him is something our team has been completely amazed by. So yes, we want all of our teams to grow, to create new things, but also things which are unforgettable. With this equation, it has been something terrific. And, as you said, it is important for us to show that, but it really is the nature of Ubisoft.

What we like about Nintendo is we have the same philosophy of creating worlds and characters that are fun, that are going to help you understand a world and be happy to live in it. So, this collaboration is not only between characters, it's between people.

Shigeru Miyamoto: The producers and directors of this game - on the Ubisoft and Nintendo side - were able to really work together. As I mentioned earlier, Ubisoft has a really good understanding of how Nintendo works, and how Nintendo works with other developers. A lot of the humour in the game as well - I think we were able to show how much Nintendo can handle some of those jokes. And because Nintendo and Ubisoft have similar views on what a product should be, I think it [has turned out] pretty faithful.

And presumably a strong and independent Ubisoft is important to Nintendo, and the industry in general?

Shigeru Miyamoto: Yes - I think you're absolutely right.

I think I speak on behalf of our readers to say - we would all agree as well.