Sprague-Grundy Value
All second-player win games have a Sprague–Grundy value of zero, though they may not be the zero game.
For example, normal Nim with two identical piles (of any size) is not the zero game, but has value 0, since it is a second-player winning situation whatever the first player plays. It is not a fuzzy game because first player has no winning option.
Read more about this topic: Zero Game