Guarding a facility, this is your outpost.

After NASA finds a way to get a renewable enery source, they use it as a reactor and find it goes faster than light speed, allowing interstellar travel. They quickly put it on a spaceship and launch it.

It all started when there was a bright star in the sky, it got brighter and brighter. NASA said it was a red dwarf headed our way, then panic begun. People realised that Earth was ejected out of the Solar System. Riots in streets, mass panic. This shelter is the last barrier you have.

The creature escaped. Nobody else got into the bunker in time. You doubt anybody will help you in this underground lab.