What is Battle for Wesnoth? (taken from official site)

The Battle for Wesnoth is a turn-based strategy game with a fantasy theme.

Build up a great army, gradually turning raw recruits into hardened veterans. In later games, recall your toughest warriors and form a deadly host against whom none can stand! Choose units from a large pool of specialists, and hand-pick a force with the right strengths to fight well on different terrains against all manner of opposition.

Wesnoth has many different sagas waiting to be played out. Fight to regain the throne of Wesnoth, of which you are the legitimate heir... step into the boots of a young officer sent to guard a not-so-sleepy frontier outpost... vanquish a horde of undead warriors unleashed by a foul necromancer, who also happens to have taken your brother hostage... guide a band of elvish survivors in an epic quest to find a new home.

Read this: http://www.wesnoth.org/wiki/Description

How it look like? http://www.wesnoth.org/wiki/Screenshots

Help?
Getting started
Manual


Download:

Mirror
URL: http://eko.dyndns.biz:8980/wesnoth
Distribution: bora
Components: user

Mirror by courtesy of blackax:
URL: http://blackax.net/Pub/wesnoth/
Distribution: bora
Components: user


URL: http://eko.one.pl/maemo
Distribution: bora
Components: user

No music, no editor, no server component. You need a lot free space (> 32 MB). Install libsdl_net, wesnoth main package, official campaign (Heir to the Throne, The South Guard, The Rise of Wesnoth, A Tale of Two Brothers, Eastern Invasion or Under the Burning Suns), perhaps locales (for non-english speaking people) and sound.

Game starting very, very slow (loading graphics), so be patient. Have fun.