A game is a structured form of play undertaken for entertainment or fun, or as a tool for learning. Games can be playful (such as hide-and-seek or tag) or competitive, with rules governing a set of activities such as racing or figure skating. Many games are also considered to be work (professional spectator sports or game theory), art (jigsaw puzzles and some board and video games), or a combination of both work and play (such as tabletop games).

There are many different types of games, ranging from simple card games to complex role-playing games with detailed world settings and character creation. All games require a goal, a means to track progress toward that goal, and some kind of interaction between players. Some games have no obvious goals or objectives beyond winning, while others, such as baseball or tennis, have a clear objective of advancing to certain points on the scoreboard.

Video games are computer programs that engage the player in a simulated world and allow them to interact with that world using controls such as arrows and buttons. Initially, video games were developed for personal computers but have now been widely adopted for use on personal devices such as smartphones and tablet PCs. There are now millions of games available for download and purchase on the various gaming platforms.

Despite the wide availability of games, there is little agreement on what constitutes a game. For example, some scholars have argued that games should only be defined by their tools and the rules defining those tools. However, this definition is problematic, as even games that have the same rules and tools can be different from one another. For example, the game of baseball can be played with real or wiffleballs, but the gameplay will differ if the rules are altered to allow attacks on the opponent.

Many games have a specific theme that immerses the player in a particular world. This can be anything from being a landlord in Monopoly to fighting monsters in a castle to monkeys in bumper cars. A good game design will carefully consider the theme and how it can be incorporated into the mechanics of the game.

Increasingly, games are being used to address important societal issues such as misinformation and health behaviors. The Misinformation Games research project, for example, uses a game to teach people about the techniques that are used in the production of fake news. This psychological inoculation helps prevent the spread of this misinformation, and can also help people develop cognitive immunity against it. This is a novel application of the game-based learning framework, and shows the potential of games as translational interventions for social change.