From what I see and can understand, the GameDev forum is as independent as it can be!
In what other way, other than being related to Games developed/developing using B4X products, it is related to B4X? And how could it be "100% independent"?
Linking both ways the threads created in the new forum, will make easier to "discover" the forums, so a user searching for LibX related stuff in B4X.com will find references to the GameDev, and users landing for the first time in the GameDev Forum will find references to B4X.com.
It's a win-win combo!
BTW, EREL didn't endorse, as I've read in a post here, the creation of the new forum... He just gave his permission to do so, as long as some conditions were met.