On November 11, 2010, InstantAction was shut down along with all the games it hosted, including Legions.  Before this, a dedicated group of community members had been working on a stand-alone client, and are still planning to release it sometime soon.  The game, now named Legions: Overdrive, can be found at LegionsOverdrive.com.  

That's cool that it's being kept alive. I usually just boot up Tribes 1 for my Tribes fix, though.

Another T1 player?  We're rare, you know?   
  
:)