I was definitely going for a subterranean terror, a fear of something you cannot see but is ever present. I'm glad you enjoyed it.
As for your question about writing a continuation - yes and no. I've tried serializing stories before with limited success. I've seen a lot of people on Steemit do that and it seems like a sensible way to build a readership, but in my experience interest seems to drop off almost immediately after the first installment, if indeed it generates any interest at all. I can also understand that - it's a little daunting to see something labeled "Part 7" and realize you'll have to read 6 other parts first if you haven't been followed all along.
Right now I'm taking a different approach. If you look at some of my previous stories, you'll see they have some overlap in characters or themes or both. In a couple cases I've written about the characters when they are adults. Rather than execute a planned serialized story, I'm taking a more experiment inductive approach. Expect to see more stories about the deep and about Sid, his brother, and their friends, but maybe not as a part of a single cohesive whole. At least not yet.
Someday I hope to assemble the various stories together into a big one. Right now I'm satisfied to put together somewhat self-contained chunks that are allowed to go in whatever direction seems appropriate without constraining them by a larger structure. Hope that makes sense.
I like how you are doing that. It is actually better than creating long series with many many many chapters. The problem which I see on Steemit is that there are so many authors and if you want to support a lot of them, you simply don't have time to read each chapter. Which is sad on one hand but on the other hand other people might get nice stories that you want to read too.
So I like your approach as it doesn't require reading prior stories. I didn't think about something like that. It's cool and unusual :)
Thanks!