Wow, I haven't updated the list in quite a while. Added the following games:
OpenGGS
An open source remake of
The Great Giana Sisters (a
Super Mario Bros. clone). The author has permission to use original graphics from the Commodore 64 version, but there's also a free tile set as well.
Annex: Conquer the World
A free, open source real-time strategy game based on the
MegaGlest engine, which is apparently inspired by the
Command & Conquer series of games, as well as
Earth 2140 and sequels,
Warzone 2100 and
StarCraft. There are four playable factions, several terrain tilesets, customizable tech trees, campaign scenarios, skirmish and mutliplayer modes.
The same developer is working on another RTS with a space sci-fi setting, called
Terra Centauri: Last Stand. A beta is available
here.
Wyrmsun
A free, open source real-time strategy game that runs on the
Stratagus engine (an engine recreation of
Warcraft II). Its art style is remarkable close to that of Blizzard's famous game, however
Wyrmsun is an original title with its own unique features like individual unit names, traits and experience points, a turn-based grand strategy mode, and a setting that blends fantasy and mythology with real historical background.
Wyrmsun is free and open source, but those who would like to support its development can buy copies from
Steam and
Desura.
There are also some other interesting titles but not yet added to the list:
openKB is an engine recreation project for New World Computing's
King's Bounty, with planned support for the original game's files as well as a free open source data set. The development is in its early stages, so no downloads yet.
Free Mars is a free, open source turn-based strategy game inspired by
Sid Meier's Civilization,
Colonization and
Alpha Centauri.
Rescue! Max is a remake of
Rescue!, a Mac shareware game.
CATharsis is a project to create an open source clone of
Duke Nukem: Manhattan Project in Blender. It's not an engine recreation, but rather a stand-alone game similar to
DNMP but with its own protagonist, art, levels etc. Rather early stages of development.
In other news, recently a Windows binary executable was made available for
LordsAWar!, a free open source clone of SSG's
Warlords II. The version is 0.3.0, which features a two single-player scenarios, random map mode, and network multiplayer.