I am wondering if any game designers have used an online implementation of a game to balance and tweak it before commercial release.
I'm pretty sure "Day and Night" was tested online before release. But the online game was only limited to a small beta testing audience. The website used to say that the online version would reappear at some point, but the website is now dead and the developers appear to have vanished.
Since Day and Night is an asymmetric game, getting the two sides balanced is important, and the developers claimed that they were very close to 50:50 based on online testing.