Some other examples not in the OP:

- A Dark Room http://blog.doublespeakgames.com/news/a-dark-room-goes-open-...

- Spelunky http://www.spelunkyworld.com/original.html

- MechCommander 2 (shared source, via Microsoft) http://www.neowin.net/news/microsoft-mechcommander-2-shared-...

- Asteroids (and many other Atari games) http://www.atarimuseum.com/videogames/consoles/7800/games/

- Cart Life http://www.spelunkyworld.com/original.html (perhaps not as commercially successful as the others...but won a huge indie game prize, and is a great work overall)

OP covered some of the best examples, but the more complete list of commercial video games with available source code can be found here:

https://en.wikipedia.org/wiki/List_of_commercial_video_games...

Spelunky was released as freeware so I'm not sure it counts.

Cart Life link is a dupe of the Spelunky link. This is the correct one: http://www.richardhofmeier.com/cartlife/editions.html (at the bottom of the page)

Hmm... I'm getting an entirely black page.

Also Star Control 2 - http://sc2.sourceforge.net/ (Ur-Quan Masters).

MechCommander 2 is in the OP.

If you want to play the original Spelunky, I suggest going with the fanmade 1.3 patch.

For a look at a commercial game currently in development that has released it's (evolving) source code, there's Space Engineers by Keen Software House: https://github.com/KeenSoftwareHouse/SpaceEngineers

May as well add my little Speed Haste (released as Circuit Racers in the USA): https://github.com/TheJare/SpeedHasteSrc

Not as noteworthy as those in the list but hey, it's mine.

I loved that game - thanks for sharing the code :-)

One of the interesting things about games is that to the end user/player the majority of the value is the art and level design, two things which are extremely easy to divorce from the source (and thus license-able under whatever) so unless you're EPIC or somebody trying to specifically license tech open sourcing a game really doesn't make a lot of difference in the business model.

that said I'll add to the list DROD (one of the best puzzle series ever):

http://forum.caravelgames.com/site/SourceCode

The engine of the mmorpg Ryzom was released as open source:

"Ryzom Core is the open-source project related to Ryzom Game. Written in C++, Ryzom Core contains the whole code (client, server, tools) used to make the commercial MMORPG Ryzom. Ryzom Core is a toolkit for the development of massively multiplayer online universes. It provides the base technologies and a set of development methodologies for the development of both client and server code."

Repository: https://bitbucket.org/ryzom/ryzomcore/overview

Confluence: https://ryzomcore.atlassian.net/wiki/display/RC/Ryzom+Core+H...

http://ryzomcore.org/

Star Control II is the game with most developed story that I have ever played. And yes, I have played Fallout too :)

Playing it, even with a walkthrough, is like watching a whole set of seasons of Babylon 5 or Battlestar Galactica.

So trying out UQM (open-source port) is a must. It also has quite good two player fighting mode.

How awesome is it that you can pickup an old game, one of your favorites maybe, read the actual source code - which might even have a modern analysis discussed at length by Fabien Sanglard - and then play the game... with all of the community's latest tweaks/optimizations... AND then ... when you come across a bug ... you can code the fix yourself!

After reading this article, I compiled Duke Nukem 3D and played enough to find something that bothered me. Just pushed a fix for horizontal mouse-look/strafing (to Fabien's 'chocolate' repo):

https://github.com/fabiensanglard/chocolate_duke3D

It's like this weird connection to the original devs ... and my childhood.

Something the author glosses over is that the Quake 3 engine is remarkably clean in its separation of the game logic from the engine--the use of "traps" gives something that very much reminds me of an operating system in some ways.

Great list. Thanks for putting together. Wish the entries had some metadata around language, size, etc. just for kicks!

Another example would be Fish Fillets. The GPL release of the source included all of the assets, even the voice-acting sound files (though only available in Czech). Info at http://fillets.sf.net/ , released source code at http://sourceforge.net/projects/fillets/files/original%20ALT...

Homeworld is the only major one I know. They just released a remaster on Steam though so I wonder how this has affected the modding community.

Source for the Atari 800 version of Donkey Kong is here

http://atariage.com/forums/topic/130904-donkey-kong-source-c...

Beware gnarly 6502 assembly language :-)

Warzone 2100, still going strong.