Battle for Wesnoth http://www.wesnoth.org/

Vulture's Eye http://www.darkarts.co.za/vulture

OpenArena http://www.openarena.ws/smfnews.php

FreeCiv http://freeciv.wikia.com/wiki/Main_Page

Naev http://code.google.com/p/naev/

UfoAI http://ufoai.org/wiki/News

AlephONE/Marathon http://marathon.sourceforge.net/

Hidden and Dangerous http://www.atomicgamer.com/files/31068/hidden-dangerous-deluxe-full-game

Scummvm http://scummvm.org/ + Game packs (scroll down) http://scummvm.org/downloads/

OpenTTD http://www.openttd.org/en/

Warzone 2100 http://wz2100.net/

Ur Quan Masters http://sc2.sourceforge.net/

Unknown Horizons http://www.unknown-horizons.org/download/

FreeCol https://en.wikipedia.org/wiki/SourceForge.net

BosWars http://www.boswars.org/

WideLands http://wl.widelands.org/