Adobe flash

Adobe Flash's main uses are DRMs (preventing the users from saving the content, pay walls, geo-blocking, etc.) and super-cookies (e.g., embedded in blinking ads) to track users. Make Adobe Flash free and those anti-features would soon be removed... and so would Adobe Flash's remaining market.

I have thought exactly that about old video games. When they're not in retail anymore, why not release them as free software? If a company did that they would probably even benefit from it financially, as such a move would put them in the news.

Firstly, there is one piece of sad news I need to break to you- Adobe Flash, unfortunately, isn't dead. It may not be the piece of web infrastructure it once was, but there is no shortage of functionality (games and legacy sites mostly) which demands it. Additionally considering Magic Banana's points above and the fact that Adobe recently revived the software's GNU/Linux port, it's not as if Flash (Crash?) is yet a historical artifact.

Regardless of that, keeping abandonware proprietary does seem to be an endemic problem. I suspect most companies simply don't even think about the possibility of freeing the code, or won't/can't because of licensing and the perception of software as a 'product', which can (like with vintage clothing and vinyl disks) go through revival phases where they once again become profitable. I honestly don't know- perhaps some companies would free their legacy code if we asked nicely?

Gnash works reasonably well and there is server side code. If you want to implement things with Flash, look at the Gnash project and Cygnal.

https://en.wikipedia.org/wiki/Gnash_%28software%29

Let Adobe rot.