My two cents worth is that some change to the process of generating the puzzles occurred. It would be possible to change the behavior of the program if it was using a random number generator in a shared library (or a DLL in the Windows world). If the shared library is changed (say as a result of upgrading the operating system) the behavior of the program could be changed without actually changing the program itself.

My guess then is that some peripheral change has effected the way the puzzle generation program works, possibly something like I just described. In that case, Dr. God might not realize that the operation of his program has changed because no direct change was made to his program.

drwho - that sounds like the most logical explanation. It never dawned on me that generator used by this site would use shared code but it makes perfect sense, especially something like a prng.

Done, no green.

Done, no green

done

done

done

KnightTime - not many programmers write their own random number generators. But usually you statically link in the library routines. However, you can use DLLs in the Windows world, or shared libraries in the Unix/Linux world where the libraries can be changed without recompiling and linking the program.

Difficulty score 14. No green.

Done

Oh yeah, I get all that.

done

done easy peasy]

I once wrote a game program that needed two, separate, random number generators. I needed to write my own for one of them because I wanted to be able to repeat the sequence. Then I wrote a program to test the randomness. Despite a loopy looking algorithm -- taking the middle digit out of a product of huge pseudo-random numbers, it was ever so difficult to get a roughly even distribution of outputs. It was good enough for my game. The sequence wouldn't repeat except after about one billion trials.
It's the falloff in Mediums and Hards that I've noticed about IronSudoku. As I often feel that the difficulty rating is misnamed, I think perhaps the only change has been, not in generating the puzzles, but in naming the difficulty.

Trivially easy. 6.

Done

go

done

Done.

And awaaaay we go

fun!

Finally made up for the wk in the Berkshires with no computer!!!