You all know Valve right? With their digital distribution platform called Steam and Game developer for games like Half-life2, Portal, TeamFortress 2, Left 4 Dead and many many more.
I mailed their one of their developers Alfred Reynolds to see if Valve had any plans to be IPv6 compatible.
Here is their short and clear awnser:
Hey Jasper, we have no firm IPV6 plans at this time.
Guess the Valve on the IPv6 pipe is closed.