This was the last panel in the first story, which ended a little before your 13th birthday. Since then, the author has been steadily updating PROBLEM SLEUTH 2, which you have been following avidly. You are happy that he stayed in that lane, and stuck with a time-tested formula. If he went in a different direction, you probably would have found it really disappointing.
Problem Sleuth 2 is a fictional adventure by Andrew Hussie. It only exists in the post-Scratch universe, and replaces either Midnight Crew (in Homestuck-verse) or Homestuck (in real life).
Its plot is unknown, but it most likely follows PS, AD and PI in Real City Streets, seeking for more detective adventures.