I've thought of re-joining one a few times. Some seem overly complicated and I dislike using Civ5, doesn't seem to lend itself well to immersion role-playing, more army tactics. Plus I've had my hands full with games on the Realms Beyond Forum.
Any games in particular that looks good at the moment? I haven't glanced round since I tried to join a Divine Intervention and found out the player had an old version of Rhyse and didn't want to upgrade. (Thus I had to not play.)