Brilliant puzzle, indeed. I have been in an on/off relationship since the puzzle was first shown on LogicMasters. Unfortunately, if I am not completely mistaken, the puzzle doesn't have a unique solution. At least, I have found a solution with the identical pattern of mines, 3s and 1s, the identical pattern of the "relevant" mines, i.e. those that contribute to the totals being given, and the pattern of all 4s and 9s. The main difference is the distribution of the 2s in boxes 1, 2 and 5 (the others being identical to the solution shown here), which results in corresponding changes of some 5s, 6s, 7s and 8s in boxes 1 to 7. Of course, the number clues are OK (since the relevant positions are all identical), the mine conditions are OK (the changes of the three 2s listed above are permitted) and all Sudoku rules are fulfilled as well.
First some comments on how I arrived at my solution. Placing the mines and the 3s and 1s was the major goal from the start, including the constraints imposed on those positions by the number of mines to appear in a 3x3 box, a Killer Sudoku box or one of the diagonals, and with some help from the numbers that were permitted or excluded from contributing to the given totals.
In the first clue shown above, there is a discussion of some reciprocity between the 1s and 3s in corner positions of the 3x3 boxes. While I agree with the first conclusion shown above, I do not agree with the forced positioning of 3s when a 1 is in a corner. At least, I could not see why a 3 could not be placed anywhere in the 3x3 box without being able to find at least one option, where all three mines and the 2 could be placed in line with the minesweeper rules. If I was wrong there, I made my life much more miserable than necessary!
The deduction of the positions of the mines and the 3s and 1s was done in a stepwise order (which is at least some boderline case of using bifurcations), where I tried to identify starting scenarios, which imposed the highest number of constraints on the rest of the grid, followed by trying to prove that that scenario didn't work, so that I could exclude the starting assumption. Since I got lost a number of times, I decided to assemple a list of the different steps I took, which finally included more that 30 entries until all mines, the 3s and 1s were completely set. Once that was done, two of the 2s could easily be identified, and the rest was Killer Sudoku/Sudoku.
I have just repeated those last steps and apparently, I had made an error on my way to solving the puzzle yesterday, since I didn't spot the point in time where the path would have split to lead to the two different options.
...and a short update: Apparently, I got carried away a bit, after I had finally been able to fix all mines, 3s, 1s, and the Killer Sodoku part, and so I apparently made an error early on in the final Sudoku part, which excluded one of the options. I have now found out that this option leads to yet another solution of the puzzle, which I have now added down below. So I am now sure that the puzzle has three solutions in total, and I can finally, after two years, put that puzzle to rest. Best regards
And here are the two solutions in addition to the one shown above:
9 1 7 8 4 3 2 6 5
2 5 3 7 9 6 8 4 1
8 6 4 1 2 5 7 3 9
5 9 1 3 8 7 4 2 6
6 7 2 9 5 4 1 8 3
3 4 8 2 6 1 9 5 7
7 2 5 4 3 9 6 1 8
1 8 6 5 7 2 3 9 4
4 3 9 6 1 8 5 7 2
7 1 8 9 4 3 2 6 5
2 5 3 7 8 6 9 4 1
9 6 4 1 2 5 7 3 8
8 9 1 3 6 2 4 5 7
6 7 2 5 9 4 1 8 3
3 4 5 8 7 1 6 2 9
5 2 7 4 3 9 8 1 6
1 8 6 2 5 7 3 9 4
4 3 9 6 1 8 5 7 2