See Puzzle 2 for instructions to the standard Quadrum Quandary puzzle (if for some reason you've been living in the proverbial cave and haven't solved a Sudoku before). In this variant, chess queens are to be used instead of '9's; none may be attacking each other in the solution.
I'm not the first person to think of doing this, but I do believe I am the first to present it as such. For the curious, there are 144 ways nine non-attacking queens can be arranged in a 9×9 grid without violating 3×3 regional restrictions (19 if rotations and reflections are discounted), so there's plenty of room for making more of these. In fact, up to seven such ways can be used simultaneously, so don't be too surprised if you see Quadruple Queens Quadrum Quandary or Quintuple Queens Quadrum Quandary in the future♥
Note there are no queens among the givens. This was very much intentional; I like to see if people actually read directions. If attempted as a standard Quadrum Quandary, multiple solutions would appear to be possible. Anyone that tells me this puzzle has multiple solutions will be publicly and mercilessly mocked. I also believe that this is the first puzzle of any chess-piece variant, built by anyone, that places no chess pieces among the givens. For the record, enforcing that made this puzzle a bloody nuisance to construct, so I hope you really enjoy it. Or at least get really frustrated at it, in which case we can commiserate each other. Future offerings will likely contain given queens. I might even find a better way of representing them in a monochromatic 5×5 pixel square than with the letter 'Q'. But I doubt that.
As always, feel free to comment on the design here, and emailing me your solution may result in your receiving a prize. Also, don't forget to post your choice for supersize Puzzle 30! - ZM