Slack was born out of the (second) attempt by Butterfield to build a game. But Slack didn't start out as a game; there was a game being built, and it didn't ev

Slack was born out of the (second) attempt by Butterfield to build a game. But Slack didn't start out as a game; there was a game being built, and it didn't evolve into Slack—they productized their internal comms (a separate thing that they built and were using in the course of making the game).