“Elizabeth wants to control her own destiny and she’d rather die than not control her own destiny,” said Levine. “We thought that this was something people could empathize with, but we also thought that sacrifice rapidly builds connections between people. People sacrificing for one another creates strong bonds quickly, and the [Infinite] demo is a microcosm of the whole game in that sense. It’s about what the characters sacrifice for each other.

“Then of course [Elizabeth] has to be nice and funny and charming, she can’t be a bore. So there’s levels of macro and micro decision making to make this stuff work. She’s there to help you throughout the game. She makes your life better. She can toss you ammo, point out enemies, to bring in the tears, and she’s a very you-centered AI. You are not obligated to take care of her in the way that you are in an escort mission.”

“We want her impacting on what’s going on all the time,” he said. “We kicked around a ton of ideas for this and eventually we started thinking about, well, you have all these tools in Bioshock games, and we wanted another way you could impact on the world that wouldn’t be too complicated – your hands are already full! – what if we took this narrative notion of things that don’t exist in your world and connect them to gameplay elements? How would that work?

“Well it’s essentially like a summoning spell, where Elizabeth has a number of summons, or desummoning! It can change geometry, it can change the number of enemies, what weapons you have, if there are turrets, you having some degree of control over that, we thought, was really interesting.”