Game Engines Should Always be Open Source
Games are another form of media we experience, but due to the richness of this media it is probably not feasible nor even a good idea to have common formats or specifications for how games should be created. How then is it possible to ensure that the games created today live on even when the systems they were created on a long obsolete? Open source them of course.
The most important part of any game is the game data, the models, maps, voice-overs, dialogues etc. The best way for any game creator to ensure that it will always be possible to play their game -- even if they no longer support or sell it -- is to make the game engine open source. The game data need not be opened, gamers will still need to pay for that if they want to play the game. id Software has the right idea in this regard as they open source their previous-generation engines, and it should be a model followed by all game creators.