Perhaps one problem with “infinite sudoku” is that valid solutions are not sparse. It can be solved by a random number generator with accuracy approaching 100%. It’s possibly for infinite valid solutions to be sparse among a greater infinity of invalid solutions though, without making a better game. Consider the formula:
10 + _ – _ = 12
This could be presented as a puzzle game. There are infinitely many valid solutions, and they’re extremely sparse, but it’s still not very fun.
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