A serial entrepreneur, Stewart Butterfield was part of the founding team which created Flickr. After taking off, it was sold to Yahoo! - where the team had a brief stint, until they came together to start their own game development company, Tiny Speck. Their first game Glitch, an online massive multiplayer, enjoyed initial success but failed to gather any real traction.
Slack had begun as an internal tool for Tiny Speck during the development of Glitch. After deciding to build a communication tool, Stewart Butterfield and his team wanted to begin at a very different starting position to a traditional business software company like Microsoft. They wanted to be a contrast to the existing communication apps, which were boring and drab.
Working on Glitch, they'd learned the importance of making every interaction interesting, fun and irreverent. The very same approach was carried forward with Slack. From the start, Slack avoided all the standard hallmarks of business software. The name was a little bit edgy and the logo and color scheme were bright, cheerful and a little bit goofy.