Death and Taxes, a narrative game about choosing who lives and who dies as the Grim Reaper is now officially open source. In an announcement on Steam written by their coder, they said their wish when joining the team was to eventually open it up and so now they have.
It's only been out since February (and I quite liked it!), since then they've gone on to sell "pretty well" at twenty-six thousand copies so they're not afraid people will copy it. Only the code is open source though, you still need the assets which is a good example of how to do it that others have also done. The game code can live on, be ported elsewhere and fixed up, while the original developer can still earn from it.
Resources which I sorely missed were concrete, specific and (most importantly) helpful examples of real-world applications of coding principles, workarounds, hacks, engine-specific behaviour, et cetera. The most helpful places were, for example, the Unity Answer Hub, Stack Overflow, the Unreal Developers' Network... they all, at best, offered a window to see how people actually implement stuff. I am a firm believer that it is usually more efficient to learn from the mistakes of others, rather than just people having to make the same mistakes over and over again due to lack of reliable information.
And this leads me to the (incredibly winding and convoluted, sorry) answer to why we're releasing the source code for our game. I want to provide something that people can learn from. Including myself. The code for Death and Taxes is by NO MEANS clean or even "good" (depends on what your standard is). But the most important thing is that the code worked. The game shipped, and the game worked.
Hat tip to Eike