Really enjoyed this! I think the setting is really strong. I was definitely interested in seeing more of it, so am interested in you saying it's a 'sort of' prequel.
I also think the general concept of how you "avoid the plague" is a really interesting mechanic. I think there's so much cool stuff with that. Certainly makes you rethink just blundering around the town as well.
I also really liked how you used the map for travelling, and the colours of the final area too.