It's been weeks since everyone on mobius started to die by a demon known as Exeller. You decided to get help by finding the Master Emerald, but upon finding it, you see another Mobian had found it first as she spoke with a bit of concern

Alice: "How did you manage to even get this far...? I thought he had already killed everyone..."

You knew exactly who she was referring to, Exeller, the same demon that took over Sonic's body.