Doomsday Dawn (DD) is the not-quite-an-adventure-path which accompanies the Pathfinder 2e play-test. It has some level gaps: the players are expected to play both "primary" characters (who get levelled up between appearances, including the first and last adventure) and other, secondary characters who only turn up for one adventure each. The secondary characters often have to be constructed according to certain guidelines,
Also, certain adventures are constructed for specific play-test goals, for example "test to destruction"/"final stand in a base under siege".
All of the above makes DD a very atypical not-quite-an-adventure-path. However, the subject matter is interesting, and offers an answer to a mystery which has existed on Golarion for many centuries: the Doomsday Clocks. It also covers at least a decade of time, and re-visits certain iconic loations from various APs and modules.
That said, has anyone thought of converting DD "back" into PF 1e?