i have downloaded puzzle booklet bt it is asking password .. what is the password to open it

The password will be visible once you click the start button and start the timer for the contest.

Thanks Prasanna! This PU episode was certainly tougher than its predecessor. Liked the squared rules.
My favorites:
1. Double Back
2. Kakuro Kakuro
3. LITS
4. Ovotovata

Thanks to all 142 participants!

Congratulations to Endo Ken, Freddie Hand, Walker Anderson, Hideaki Jo, Kota Morinishi and Jeffrey Bardon for completing the set within the time. The top three remain the same from Parallel Universe III.

Among participants from India, Congratulations to Ashish Kumar, Swaroop Guggilam, Rajesh Kumar and Harmeet Singh for top four positions.

Among puzzles, not surprisingly, Stostone proved to be the toughest. Among squared Puzzles, surprisingly, Double double back proved to be the toughest.

Ovotovatatavotovo (like its spelling) was the most error-prone puzzle.

Thanks Prasanna Seshadri for the variety of puzzles in this test.

Thanks a lot Prasanna for such a great contest. I enjoyed this contest a lot and would be the best puzzle contest I have solved in recent times. Great puzzles with greats Themes and ofcourse stunning solving path.

The Solution Booklet is now available here.

Thank you to everyone who participated in this as well as Parallel Universe 3. The last 2 installments were a challenge from the perspective of coming up with ideas that work interestingly within the respective themes and I'm generally happy with how things turned out and I am glad that people seem to have enjoyed the contests in general.

Congratulations to the winners. The top 3 have been the same across both contests, with just a swap between 2nd and 3rd places, which shows that these solvers are skilled at sprint solving as well as solving tougher puzzles. Really impressive performances.

Thank you to Rakesh, Murat, Philipp for their help with putting this together, and of course to Swaroop for his continued work on improving penpa-edit.

Feel free to ask doubts about the puzzles here :)

You can also see two videos covering puzzles on the contest so far.
Simon Anthony's runthrough of the Kakuro and the Kakuro Kakuro - https://www.youtube.com/watch?v=QBihIeXcL6I&t=1909s
Ashish Kumar's solve explaining the difficult logic on the Stostone puzzle - https://www.youtube.com/watch?v=_ghwaabIDk0
I recommend viewing both videos. They were both informative about the puzzles covered.

Hardly an urgent issue, but the results of this contest appear not to be visible.

Available now.