Developer Undead Labs and Microsoft have added new weapons, vehicles and characters for State of Decay: Year-One Survival Edition on PC and Xbox One.

Undead Labs also added a new mission type as well as improved the visuals, animations and user interface for this new version of the simulation-driven open-world zombie survival game.

We already knew Year-One Survival Edition includes the Breakdown and Lifeline modes that were added to the Xbox 360 version as downloadable content.

Breakdown is a rogue-like, never-ending survival mode that gets harder as time progresses. Lifeline is a narrative-driven storyline adventure set in the city of Danforth. Both are in Year-One Survival Edition.

Usefully, the military weapons and hardware added to the Xbox 360 game with the Lifeline DLC have been added to the other two modes for Year-One Survival Edition. Characters from Lifeline have been added to Breakdown, too, as well as certain abilities. For example, being able to create ammo in a workshop in your base was an ability created for Lifeline that is now added to the rest of the game.

There's also a new mission type. Here a mysterious organisation is airdropping supply crates onto the map at random locations. While these crates include some of the best weapons in the game, they're extremely difficult to open as they attract a huge number of zombies and freaks.

A new mission type sees supply crates drop onto the map at random locations. They create a lot of noise.

In keeping with Undead Labs' focus on the State of Decay community, those who played the original get 33 per cent off Year-One Survival Edition. That discount works going from PC to PC, and Xbox 360 to Xbox One. Those who upgrade also get an exclusive character, Gurubani Kaur, who packs a suppressed rifle - the only one in State of Decay. And, you can transfer your save game across from Xbox 360 to Xbox One in the same way Xbox 360 players of Minecraft were able to when moving to the new console.

As you'd expect, the visuals have been improved. Year-One Survival Edition uses the same engine, Crytek's CryEngine 3, as the Xbox 360 version, but with improved animations, bug fixes, texture bumps, a better draw distance and a 1080p resolution.

This, Microsoft says, has a tangible gameplay benefit, as you'll be able to spot zombies and freaks from farther away than you were able to on Xbox 360. You'll also be able to read the many signs placed in the world, some of which include nice backstory detail, such as a gas station that went bust before the zombie apocalypse. These signs were difficult to make out on Xbox 360.

Gurubani Kaur is a new character exclusive to those who have played the original State of Decay.

The user interface has been a particular focus for Undead Labs. It's fair to say the Xbox 360 version suffered from a cumbersome interface that poorly managed its many systems.

So, the user interface has been tidied up in a bid to surface features that were previously buried.

"It's a pretty complicated game," Seb Grinke, game designer at Microsoft Studios, told Eurogamer. "There's a lot going on and you have a lot to do. We did a tonne of user research testing at the user research lab at Microsoft. The feedback we got was some people were struggling with the UI. Redoing that unlocks some of the elements of the game people didn't even know where there.

"Each character in the game has a number of traits from their former life before the apocalypse. So if you're playing a character who was into hunting before the apocalypse they're going to be awesome at the shooting skill.

"So there's a tonne of depth in terms of what items you have equipped and who you use for what task. A lot of that was buried in the original game. Now it's much clearer and easier to see what the skills are, how to level them up and how to min/max your characters."

While Undead Labs and Microsoft managed to get State of Decay running at 1080p resolution on Xbox One, it failed to bump up the visuals to 60 frames per second. Instead, it settled on 30fps.

"There's a lot going on," Grinke replied when asked about the game's frame-rate. "You've got this whole community you're managing. You've got all these player characters, NPCs, tonnes of zombies, cars, there's just so much going on in the world that 30 made sense."

Year-One Survival Edition includes the modes Breakdown and Lifeline.

Neither will Year-One Survival Edition have a co-op mode, which Zombie Studio did at one point try to make work. According to Grinke, it turned out Undead Labs would have had to rework the game engine to get co-op up and running, and even then not to a quality level it would have been happy with.

"They looked into it," Grinke said. "They discovered in order to do it, they would have to rewrite a large percentage of the code. I've experienced it before in other studios I've worked at where, you think, I'll do co-op, but then you get into it and you're like, holy s***, we'd have to re-architecture most of the engine to make this work.

"They decided, we can either do this co-op thing and it's going to be a band-aid on the existing game, or we can not do that and focus on just making a fantastic single-player game, where there is the opportunity to share your story on Twitch, with different ways of achieving that multiplayer with the community wiki, then look at doing multiplayer in the future."

The future for State of Decay looks bright indeed. The Xbox One and PC follow-up was an obvious move considering State of Decay is the fastest-selling new IP ever on Xbox Live Arcade. And then? Year-One Survival Edition, due out 28th April worldwide for Xbox One and PC (via Steam) for ₤19.99, is just the first next-gen step for State of Decay, as Microsoft has signed a multi-game deal with Undead Labs. Surely multiplayer will be included in the inevitable sequel.