I just came across a freeware game called Widelands. It is heavily based on The Settlers and looks interesting.

http://xoops.widelands.org/

It looks like a lot of development and on going support is active in its development and community. Graphically however it doesn't look as pretty to me. This is probably because it isn't using the sprite style of the original Settlers games, and has instead opted for a full 3D and slightly ugly game engine.
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