Even then there are often immutable meta-rules!

Crawford’s definition may thus be rendered as: an interactive, goal-oriented activity made for money, with active agents to play against, in which players (including active agents) can interfere with each other.

Games can be characterized by “what the player does”. This is often referred to as gameplay. Major key elements identified in this context are tools and rules that define the overall context of game.

Many game tools are tokens, meant to represent other things. A token may be a pawn on a board, play money, or an intangible item such as a point scored.

Games such as hide-and-seek or tag do not use any obvious tool; rather, their interactivity is defined by the environment. Games with the same or similar rules may have different gameplay if the environment is altered. For example, hide-and-seek in a school building differs from the same game in a park; an auto race can be radically different depending on the track or street course, even with the same cars.

Whereas games are often characterized by their tools, they are often defined by their rules. While rules are subject to variations and changes, enough change in the rules usually results in a “new” game. For instance, baseball can be played with “real” baseballs or with wiffleballs. However, if the players decide to play with only three bases, they are arguably playing a different game. There are exceptions to this in that some games deliberately involve the changing of their own rules, but even then there are often immutable meta-rules.