Celebrating 20th Anniversary Hi-Rez Studios gift 7 free games, the 2 earthsiege and 5 Tribes games.
Link to Official Site (download)
The games are:
-Earthsiege
-Earthsiege 2
-Starsiege: Tribes
-Tribes 2
-Tribes: Aerial Assault (ps2)
-Tribes Vengeance
-Tribes Ascend (online)