In several of the cases listed here, the game's developers released the source code expressly to prevent their work from becoming lost.
Such source code is often released under varying (free and non-free, commercial and non-commercial) software licenses to the games' communities or the public; artwork and data are often released under a different license than the source code, as the copyright situation is different or more complicated.
The table below with available source code resulted not from official releases by companies or IP holders but from unclear release situations, like lost and found games, and leaks of unclear legality (e.g. by an individual developer on end-of-product-life) or undeleted content.
[271][272][273][274][275][276][277] For instance, with the closure of Atari in Sunnyvale, California, in 1996, the original source codes of several milestones of video game history such as Asteroids and Centipede were all thrown out as trash.
For example, comments and function names cannot be restored if the program was compiled without additional debug information.