Mate in one move.

WELL I ALSO DIDNT SEE THAT PIN LOL

Is Qa1# the only solution?

Yes, see my diagram above which considers all other possible checks.

20 seconds. a question of luck, depends on which one you focus first. 1471

120 seconds. FIDE rating 2133.

I found it harder than most tactical problems rated 2800+ here.

I have to think that people who "solved" it in under a minute simply didn't see why their move was wrong lol.

Took me about 2 minutes... I got frustrated and just started looking at every possible check one by one until I found it lol :)

2 minutes, 1000

Haha, I'm guessing that MANY who think they got it, don't really have it! Another good part of the puzzle is HOW MANY PASSED PAWNS were there?  In the old days, a King was always wary of someone who was just TOO good, some "White Knight, in shining armor", who might possibly have an eye on the Throne.  I guess my rating is no fluke, 1845 today and soon to rise considerably from some games that are won, just not over.  Live long and prosper.

Guess what else, there are TWO SOLUTIONS!!!!

Did you compose yourself?? Very nice one!!

I don't think the time to solve it is really correlated to rating.  No matter how high your rating, solving it is just a matter of trial and error. 

Look again Carlsen.

30 seconds rating around 550

10 secs. 1600

I "solved it" in 10 seconds, then I found the white king and noticed the rook I moved was pinned. It then took me a full minute of trial and error (what pieces can I move, how many checks are there and which of the checks I cn make is a checkmate).

Nice puzzle, mate!

Nice puzzle.

Honestly, it took me a few minutes, I wasn't really timing myself, though, so that's an estimate.  USCF rating around 1450.  Very interesting puzzle!

30 secs around 600 rating (lolly low)

10 sec.