In "Hiroimono", do we have to pass all stones or only the white stones? Rules state only white stones but that won't result in a unique solution.

You need to pass all stones. Grey markings are only for the answer key.

It appears that the example puzzle for Cross The Streams got column 2 cut off a bit.

The Icebarn example has an incorrect solution. In the upper right, two arrowheads collide along the solution's path. There is a solution, it's just not that one.

Also, the third row should probably have the symbols switched.

Can the digit repeat in the answer for Mastermind?

Yes the rules do not prohibit the numbers from repeating.

Hebi Ichigo: Can snake touch itself? i.e. can 1 and 5 of of same snake touch, or 2 and 5 of same snake be adjacent? If so, then I could not infer this from the instructions.

Will the online interface be available for IPC Puzzles?

Yes Penpa interface will be available for IPC.

Yes in Hebi Ichigo, the snake can touch itself.

For unofficial or International players, when can we solve on ISC?

Here is the changelog:
1.8: Mastermind: Instructions clarify how repeated numbers are to be interpreted.
2.6: Pencils: Rule clarification for size of the line is same as size of pencil. Also all cells need to be used by either a pencil or a line. Updated example with unique solution. Updated example answer key.
2.9: Summon rules, explaining the interpretation of the outside clues.
2.13: Hiroimono: Rule clarification, all stones need to be picked up, grey shading of stones is only for answer key purpose.
3.2: Cross The Streams: Updated example.
3.4: Icebarn solution and example answer key corrected.
3.9: Hebi Ichigo, Rules updated to clarify that each snake can touch itself, even orthogonally.

Assuming you meant IPC. It will be open till Wednesday midnight IST.

Thanks! I had a mistake about the name of the championship...

In the Maxi Loop Example, the 1st answer key has to be 24 instead of 42.

It says PB will be uploaded later.

Available now. Refresh the page.

Attachments
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Results after Round 2 ipc.pdf (110KB - 30 downloads)

Attachments
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Final Results ipc and pr 2021.pdf (112KB - 50 downloads)

How many pages are in Puzzle booklet ?

Thanks to all the organizers for conducting a smooth and successful IPC. Congratulations to Prasanna for winning comfortably and Swaroop for the podium!
Shoutout to Nityant (again!) for a terrific performance to win PR and Harsh and Mihir to complete the PR winners. Hope to see you at WPCs soon.

Puzzle quality was high and all 3 rounds were enjoyable. Some of my favourite puzzles:
Summon (mind-blowing construction and by far my favourite puzzle of the championship)
Maxi Loop
Icebarn

Rest of my feedback is pretty much the same as shared in ISC.

Once again a huge thank you to all the authors and test-solvers for the time and effort put into this event.

Thank you to all the organizers, testers, authors for a great event. Congrats to Prasanna and Rohan for the podium finish. Congrats to Nityant, Harsh, and Mihir for winning PR.

Puzzles were excellent and still need to solve many of them, so will provide the favorites later.

I rather had a terrible day, Starting with Round 1 - I went for Canal View at the start and it backfired. I was making some constant mistakes and after 30 minutes of solving I gave up with the fear of scoring 0 in the round. I then started solving the remaining puzzles. I guess the blessing is I still could get a few decent points in 30 min.
Round 2 went much better. Round 3 again was a miss with 4 broken puzzles left unsolved at the end (Double Cross, Scrin, Hebi Ichigo, Nemo).

I am happy that I could still make it to the podium.

Some nitty-gritty, I for some reason thought R3 was 90 minutes because all the R3 pages in the IB had 90 minutes written on them, and was wondering how the timer went so fast during the contest (haha), but none the less smooth event with speedy results after each round.

Looking forward to next year's event.