Instructinator

What is a game?
Jesper Juul’s definition is: “A game is a rule-based formal system with a variable and quantifiable outcome, where different outcomes are assigned different values, the player exerts effort in order to influence the outcome, the player feels attached to the outcome, and the consequences of the activity are option and negotiable.”

I agree with the first part: “A game is a rule-based formal system with a variable and quantifiable outcome, where different outcomes are assigned different values, the player exerts effort in order to influence the outcome,…”
This is essentially the prime directive for interactivity, Choice.
But requiring the player to feel attached to the outcome, or asserting that consequences in games all have negotiable outcomes by definition is a bit restrictive for a definition of all games.

If you take this definition from a different standpoint, it could be a definition that developers could strive to achieve for every game they make. Because games that do fit this definition, in all aspects of their mechanics, would only be better for having it.