Yes, rules are needed for a game. But is it enough?
e.g. there are rules to writing a syntactically correct program; ways to drive a car; use a GUI. Does that make them games?
If a user can make a game out of them, what do they add, to make it into a "game"? Is the thing added an objective of some kind (i.e. a win condition)?
That's why I added that a game is something you "play".
I'd suggest that in order to make something into a game, the user is adding "playfulness", which is pretty subjective and may or may not include a simple goal.
In an open game or fun simulation, the player is going to be coming up with their own goals or roles of play. Or maybe they will just be going with a simple open ended goal of curious exploration.
e.g. there are rules to writing a syntactically correct program; ways to drive a car; use a GUI. Does that make them games?
If a user can make a game out of them, what do they add, to make it into a "game"? Is the thing added an objective of some kind (i.e. a win condition)?