Apocalyptic Survival (Zombie Apocalypse AU)

An AU of my main story "Faded Colours"
(Concept takes heavy inspiration from "Dying Light")

There has been an outbreak in Chimestill, a virus has spread, and there seems to be an apocalypse rising.
A timid, frightened Sophie, left to fend for herself after she is abandoned, meets the group of survivors who all reside in a run down Business building they managed to secure from the infected. There she finds a young group of teens who go on missions and some other things like that (e.g. Scavenging) with the adults, and sometimes on their own. These type of people are called "The Sprinters".
That's where she meets a varied friend group.

The optimistic and energetic Luna, who's trying to keep everyone on the bright side of their minds.
Luna's twin brother Ethan, who's serious and calculating, always making sure tasks get done.
Zeia, a studying scientist who collects data for the Doctors in the zone, trying find a cure. She's not the greatest with normal weapons, but she makes great gadgets to help the team.
Dillon, a another genius in the group. He takes on more of the planning stage for missions, or "quests" as he and Luna call them. He knows the weakness' and strengths of each team member, and so helps assign them to the best jobs.
And the young Scarlett, the little girl Luna and Ethan took in as a sister after her parents were infected. She's usually colouring in the planning room we're the group are most of the time.

Sophie decides she wants to help them in any way she can. She decides to become a "Sprinter" and she joins Luna and Ethan on the "action" part of missions. Or "quests", even. She learns about each type of infection and other survivors, and finds there are some survivors who you cannot trust.

All the group can do is stick together, and, as one of their favourite game quotes, say-
"Goodnight, Goodluck."