I’m not sure. I think whole series are counted in challenges, but that’s more of a personal choice thing. Great story, original and horrifying monsters!
You need to change “the factory to door” to "to the factory door.
You might also reinforce your premise that the creature’s tongues are amazing weapons by changing “breaking through” to something that includes some great tongue action, like “licking through”, “tasting their way through”, “tonging through”,……you get the idea…..
They aren’t using their tongues to break through – the first line was written to convey strength in their limbs, despite an appearance implying the contrary.
dastardly creatures! nice work. There is a way to link them, but I cannot explain it, please see the link and try it out, or look it up in ’Notes" on the forum http://ficly.freeforums.org/writing-stories-with-multiple-linkages-t16.html