Online Required for Play Games Achievements?

[vagabond251]

Hey everyone. I just got back into the Android scene with a Nexus 7 and a SHIELD portable. I've been playing tons of games on both and loving the "Play Games" App that wasn't there last time I checked in which was a while back. My question is: Do you have to be logged in and connected to Wi-Fi for Play Games Achievements to unlock? I notice the "Welcome [Name]" thing that pops up when I start some games when not connected to Wi-Fi so I assume it's communicating somewhat with Play Games but on a few it does not unless I sign into Google+. The main game in question for me is Asphalt 8 which has it's own achievements and Play Games achievements.

Thanks in advance!