If you're looking to actually open mysterious files like this, here is how you use the real 7-Zip tool safely:
Since you're looking for a good story, here is a short piece of fiction inspired by that enigmatic file name. The Archive at Sector 16
While "s16first.7z" sounds like a specific file name—perhaps from a game mod, a creative project, or a technical archive—it doesn't point to one well-known legend. However, the name itself feels like the beginning of a digital mystery.
Elias felt a chill. He looked at the timestamp. It was dated tomorrow.