Butterfield [1] started a company to develop a game, but during their interactions the employees created some photo sharing code which ended up as Flicker, which he then sold off. Butterfield then started another company to develop a game, but to make internal company communications more efficient they developed some chat software which ended up as Slack, which he then sold off.

I have not heard if Butterfield has started a third company to develop a video game.

[1] https://en.wikipedia.org/wiki/Stewart_Butterfield