Previously, video streaming sites were at the fringes of online social media. In the past two years, live streams of video games, on sites such as Twitch.tv, have become very popular. Live streams serve as meeting grounds for player communities. The Twitch streaming medium combines broadcast video with open IRC chat channels. In conjunction with gameplay, viewer participation and community building gain emphasis. Twitch streams range in size and nature, from intimate communities with fifty viewers, to massive broadcasts with tens of thousands. In this paper, we present an ethnographic investigation of the live streaming of video games on Twitch.We find that Twitch streams act as virtual third places, in which informal communities emerge, socialize, and participate. Over time, stream communities form around shared identities drawn from streams' contents and participants' shared experiences. We describe processes through which stream communities form, the motivations of members, and emergent issues in the medium. Finally, we draw from our findings to derive implications for design of live mixed-media environments to support participatory online communities.

A rich element of cooperative games are mechanics that communicate. Unlike automated awareness cues and synchronous verbal communication, cooperative communication mechanics enable players to share information and direct action by engaging with game systems. These include both explicitly communicative mechanics, such as built-in pings that direct teammates' attention to specific locations, and emergent communicative mechanics, where players develop their own conventions about the meaning of in-game activities, like jumping to get attention. We use a grounded theory approach with 40 digital games to identify and classify the types of cooperative communication mechanics game designers might use to enable cooperative play. We provide details on the classification scheme and offer a discussion on the implications of cooperative communication mechanics.