0AD is a FREE open-source time-period strategy game.
The graphics are timeless and beautiful!
The Alpha 13 Megadha
Its Free, so you have not excuse but to try it out!
By the way, 0 is a zero, so its Zero A.D.
0 A.D. Provided Packages
Alternatively, 0 A.D. packages are available from 0 A.D. PPA:
Press EnterCode:sudo add-apt-repository ppa:wfg/0ad
Press EnterCode:sudo apt-get update
Press EnterCode:sudo apt-get install 0ad
(If you get errors about unmet dependencies, check that you have the Universe repository enabled in/etc/apt/sources.list.)