Overview of 6 open-source games: Wesnoth, AssaultCube, Hedgewars, Xonotic, Neverball, Warzone 2100.
I must agree, there aren’t many native strategy games for Linux, especially not those who can usually match the commercial ones for Linux. Actually they are so rare, they could probably be counted on the fingers of one hand.
Warzone 2100 is a free, open-source real-time strategy game available for Linux, Windows and Mac. This game was originally closed-source, developed by Pumpkin Studios and published by Eidos Interactive in 1999, but in 2004 it was officially licensed under the GNU GPL.