Riot 0.9.5 for Mac can be downloaded from our website for free. Riot for Mac lies within Communication Tools, more precisely Texting & Video calls. This free Mac application is an intellectual property of Vector Creations Ltd.
From the developer:
Riot is a shared workspace for the Web. It is a place to collaborate, work, and discuss your current projects. Riot removes the barriers between other apps, allowing you to connect teams and functionality like never before. Riot lets you run your own server, and provides users and teams with the most advanced crypto ratchet technology available today for a decentralized secure Internet.
You may want to check out more software for Mac, such as League of Legends, Doomed Heretic or Hammer, which might be similar to Riot.