From Irving Chernev's delightful book, Practical Chess Endings.

Composer: Kantorovich, 1952

Hmmm, that was interesting. Took me a while to see exactly why the threat of the discovered check from the queen was so important.

Although a simple promotion to a queen on the first move should have worked as well...admittedly it becomes a draggy Q+R vs Q game after that and is less efficient, but hey, it works.

EDIT: Argh, me being stupid, didn't see the note on perpetual check...should have been obvious in hindsight.

i don't understand 3..Kh2 black could simply just check white,even if he would be check on the next move the mate wouldn't happen

That's the beauty of this particular discovered check...any Black queen check on the third rank allows White to play the discovered check Kf2+ with mate on g2 to follow; while Qf7+ allows Kg3+ followed by Qg2# as well. Disregarding the silly checks on the a8-h1 diagonal, f4 or g4 that just hang the Black queen; the only check left for Black is Qf1+, which is met by the neat little combination 4. Kg3+ Kg1 5. Qa7+ Kh1 6. Qh7+ Kg1 7. Qh2#.

EDIT: Oh, just noticed that all these variations are available in the movelist for this puzzle. It was fun working out the possibilities though.

I got the main line but the other possiblities are fascinating.

7. Qxc1 would be checkmate

stupid of me

Because it said tactic it was the first thing I tried... the Rh1 sac.  I had no idea if it worked, but was the only tactic that came to mind... I was surprised when it was wrong and so looked up solution... turns out it was right?  It won't let me move 2.Rh1+ oh well, nice puzzle.

The new chess.com servers probably have some more bugs to fix.

grate puzzle also me it didnt let to do the right move

still grate puzzle