Finding the Invalid Move

No black-to-move tricks with this next one. Again, 1 invalid move:

Nb1+, Bc1+, Qd1+, Ke1+, Bf1+, Ng1+

Ng1+ is invalid.

That is correct! Well done.

Here’s another puzzle. Slightly easier, but with 2 invalid:

b1=R+, c1=R+, f1=R+, g1=R+, 0-0+, 0-0-0+

No 0-0, c1R:

Correct again! It’s almost symmetrical apart from the castlings, which break the symmetry and prevent wK at e1.

I guess it’s kind of repetitive with me posting a puzzle and you posting the solution after, so I hope there are more people in the future. This puzzle type definitely has some potential, but it is very unorthodox and making hard and interesting puzzles are quite hard. I’ll keep posting though if I have any interesting ideas.

i am here

if it is easy enough

and if you post it sometime between 4 pm and 10 pm ist

Kxc1, Kxd1 ,Kxc2 ,Kxd3 ,O-O

not this again

if 0-0 was possible, then the king would have to be on e1 and xc1 xc2 and xd3 are impossible

and if it was a white king then anything on d3 would protect something else 

New puzzle, 1 invalid move. There are 2 possible answers.

0-0-0, Kxd2, Kxf2, Re2+, e5, Qe8+

theres the good old trick

the other one seems to miss me for now

That’s one solution, with black to move. What about the other solution, where it’s white to move?

No Re2+:

Correct! Re2+ is invalid with white to move, 0-0-0 is invalid with black to move. The white-to-move solution was the original idea, but I thought it would be nice to add the easier black-to-move variant in.
By the way, these little “black-to-move” tricks were in fact inspired by one of your old posts on this thread (#51, #52). I hope they’re not too annoying

"Black to move" is fine. Seems the genre needs help with more ways to make problems.