Metro: Exodus was a massive surprise when it was revealed at the Microsoft E3 press conference on Sunday night. It was one of the precious few big games that hadn’t been revealed or leaked before the start of the show.

It was also a very welcome surprise. Metro: Last Light was one of 2013’s best games and we hadn’t heard a peep about a sequel in the intervening four years.

While the game looks and feels like a Metro game, Exodus is a departure for the series in one very big (and very literal way). Exodus is going to tell the story of returning protagonist Artyom and a small group of survivors leaving Moscow, the setting of the previous two games:

“You get on this train and go on an epic cross-continental journey to find something new [and] better.”

How this translates to the gameplay is a fascinating question. Both Metro 2033 and Metro: Last Light found players spending most of their time navigating the cramped and claustrophobic tunnels of the Moscow metro, with the occasional trip to the irradiated surface.

Now it seems that we’re not only leaving Moscow behind, but we may well be leaving Russia behind entirely, which is an exciting prospect. Getting out into the world beyond Moscow and seeing what’s happened elsewhere since nuclear bombs obliterated the planet is an appealing prospect.

4A Games is opening up the world in more ways than one. While not completely open world, Metro: Exodus will include nonlinear locations for the first time in the series history:

“We’ve been calling [Metro] survival horror in the past. This one in particular, we’re introducing these nonlinear levels. In the past the Metro games have always been pretty linear and story-driven. This one is still story-driven and we do still have the classic, linear Metro levels but we also have introduced new levels [like the one in the demo] that are nonlinear, larger and sandbox survival.”

Another first for the Metro series that was shown off in the gameplay demo was the season. Metro games have always taken place during Nuclear winter. Exodus’ story takes place over a full year in which players will be able to see full seasons as they progress.

The demo that was shown at Microsoft’s conference took place during Autumn, which is why the surface looks so different from previous games. The world isn’t stuck in a permanent winter anymore, which is evident by the fact that Artyom can breathe on the surface now.

Metro: Exodus is scheduled for launch on PC, PS4 and Xbox One sometime in 2018.