Rocket Chat may be dead (and truth be told it was kind of a pain in the ass anyway), but I’ve got something better to replace it with: Babble!
Now you can finally live out your dreams of conversing with other CoGers in real time on the forums, assuming those were your dreams. Access Babble chats with the megaphone icon right next to the search icon, up near your avatar:
There should be a general chat channel available to anyone who wants to use it, and any of the mods can create additional channels as requested.