Good job so far!
Overall, this is a solid start. I do like Katrina, and I like how the first official chapter (after the prologue) was introduced like a hunt but it turned into a game of capture the flag. It kept me interested and wanting to find out what happens.
Read the story now
I do think running this through a grammar check (Grammarly is great!) would help the overall grammar, punctuation, and other mechanical issues. There are some run on sentences, and some details that could be tightened up. For instance, instead of repeating the snow was fluffy, you could compare it to something, or use other adjectives to describe it. Let your readers know how Katrina feels and what's going on in her mind using internal dialogue- don't simply tell us.
Good start though! I'd be interested in reading more.