I figure a good place to start is to talk about Battle for Wesnoth.
Westnoth is a Turn Based Strategy game with RPG elements.
The graphics aren't spectacular (though they're sufficient), but the gameplay more than makes up for that. Your characters can level up as you go along. Capture towns to earn more gold.
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Type: Open Source (Completely Free)
Platforms: Windows, Linux, Max
Modes: Single Player Campaign, Online Play
Download From: http://www.wesnoth.org
