An Epic in the Making
I can definitely see the inspiration going into this book. While 'end of the world' and dystopian themes are hardly new, the characters are fresh and realistic. Instead of the gray angst clouds of other similar stories, they laugh and live like they plan on winning this fight. I like that, and that sets this plot at an easy 5 star for me.
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The author's vision is conveyed well enough, but that's where I would point out the biggest struggle in fiction. When writing action, it's easy to get caught up in the energy and write in a blitz. I had to reread several times to understand what was going on. While I completely understand first drafts are a hot mess, I would caution about focusing on description, so your reader doesn't get lost. If you want others to see what you do, sometimes, you have to slow down. Just because the action is quick doesn't mean the words have to be. By all means, though, get the ideas down, so you can flesh them out later.
I hope that helps! There's a great foundation as far as world-building and mechanics here, so keep going!