Screenshot from 2005:

'ORTS is free software. It is licensed under the GNU public license (GPL).'
The last time that webpage was updated significantly was 2005, but the game is still being worked on at least up to 2009. I cant find any better webpages for it though.
You can get all the content here:
svn://anonymous@bodo1.cs.ualberta.ca:/all/pubsoft/orts_dat
They are in the quake 3 model format, MD3. An MD3 importer for blender can be found here:
http://www.moddb.com/games/quake-iii-ar ... xport-tool
Here is one in spring. Its not much, but its better than a lot of the stuff we are getting on with.

Ill take a look at some others, there are probably at least a few good ones, for chickens and the like.