TEF is The Endless Forest, a mmorpg/interactive screensaver in which you play as a deer spirit, wander around in a pretty forest (that never ends, hence the title), cast spells, change your deer's appearance, and interact with other players. There is no 'chat box' like there is in FH, so you communicate with other players' deer characters using sounds and body language (pawing the ground, shaking your head, rolling over, cocking your head to one side, etc.)
The only place where TEF players really 'talk' is on the TEF forum/community site.
It's a very interesting and unique game, but it's not everybody's cup of tea. You either like it or you don't.