另类实境游戏（Alternate reality game，简称ARG）是一种把真实世界当作平台的交互式剧情，通常会包含多媒体与游戏元素，另类实境游戏的故事情节可以被参加者的想法或行动改变。

另类实境游戏中需要玩家的大量参与，剧情的发生是即时的，而且会受到玩家反应的影响。相对于传统电玩中，角色是被游戏中的人工智能所控制，角色在另类实境游戏中是被游戏的设计者所控制的。

玩家们直接与另类实境游戏中的角色交互，一起解决设计好的挑战或是谜题，也经常以一个社区的方式来分析剧情并协调现实生活与进行中的活动。

一般来说，另类实境游戏使用各式各样的媒体来传递消息，例如：电话、电子邮件或信件。

An alternate reality game (ARG) is an interactive networked narrative that uses the real world as a platform and uses transmedia storytelling to deliver a story that may be altered by players' ideas or actions.

The form is defined by intense player involvement with a story that takes place in real time and evolves according to players' responses. Subsequently, it is shaped by characters that are actively controlled by the game's designers, as opposed to being controlled by artificial intelligence as in a computer or console video game. Players interact directly with characters in the game, solve plot-based challenges and puzzles, and collaborate as a community to analyze the story and coordinate real-life and online activities. ARGs generally use multimedia, such as telephones, email and mail but rely on the Internet as the central binding medium.