Mirror's Edge was well known for its clean and crisp world, but it's hard to create a city that looks that clean without risking to make it look artificial. Senior Produrcer Sara Jansson explained how the team avoided that problem during a chat at Gamescom.

We have worked really heavily together with Frostbite on a specific reflection technology. [...] and we're probably gonna see in other Frostbite games later as well, but we're kind of the team that has developed it. It's a combination of three different reflection technologies that just makes this very clean world come to life with how everything reflects in the environment.

For us it was really important to have that, because since the world is so clean, we need to have that to make sure that it actually comes alive. In many other games we can hide stuff with dust or grit or dirt, here everything is so nice and clean and pristine. We invested quite heavily in this feature when it comes to rendering, and in many other features.

Jansson also stressed the importance of the streaming technology used for the game, as it's not based of huge semi-empty landscapes, but on a cityscape full of skyscrapers and objects that need to be interacted with:

Also, Mirror's Edge is quite different from other Frostbite games, since first of all we're not physics-based, we're more animation-based, and we're also not building the game on huge terrains, like Battlefield, we're actually building buildings, and everything is interactable, because everything is gameplay basically. So I think that the streaming technology of Frostbite was really important because we has this huge vista, which is a city. Everthing is made of objects and you need to interact with everything.

So the streaming technology... Without that we couldn't be doing this without any loading screens, fluidly moving through the city.

It's actually really advanced to build this type of city. I think that the engine was at the start built for huge terrains, not for huge cities with millions of objects with them. That has been kind of a challenge. We worked together with Frostbite on how to do that, so that we could actually build this big city which is all about gameplay.

If you're unfamiliar with streaming tech applied to games, it's what allows an engine to load in memory the assets needed for a location as the player moves into it, while unloading those that have been left behind at the same time. Without it, open world games would not be possible, as their objects would never fit in the RAM if they were loaded all at the same time.