Beginning with the launch of the Nintendo Entertainment System in 1985, console manufacturers have instituted policies that require developers to be officially licensed in order to produce and release games for their hardware. To back these policies up, the consoles also typically have measures in place to prevent the use of unauthorized software. These measures were instituted as a means of keeping the game market under control in order to prevent floods of poor, barely functional games from flooding store shelves, as was the case that led to the video game crash of the early 1980s.
However, such policies have not prevented some developers and publishers from finding ways to work around them. Developers would find ways around the security measures and even go so far as to produce their own cartridges in order to publish and distribute their games without authorization. Some of the more notable games of this sort, such as those produced by Wisdom Tree, were thematically religious and included titles such as Bible Adventures and Super Noah's Ark 3D. However, such titles were also not subject to any form of quality control and were often poorly designed, if not riddled with bugs that made them borderline unplayable.
More recently, some small developers have taken the enterprising approach of producing games for consoles such as the NES and Sega Genesis that are no longer supported by their manufacturers.