[ludsan]

I think Sudoku can be very fun to play with new rules, when you begin thinking in higher abstractions. I'm a big fan of anti-knight rules.

I look forward everyday to see what new puzzles are out on the Cracking-the-cryptic channel.

IMO, your use of the word 'satisfying' is to me the definition of fun!

[macintux]

Negative constraints like anti-knight significantly improve my enjoyment of Sudoku. They make it more likely that puzzles don't devolve to straight Sudoku near the end.