A few years back Kai Backman released a game called Space Station Manager. Over time, that game evolved into a grander project called ShortHike. ShortHike was originally developed with C++, but a couple of years ago Kai began the transition to D.
I was just checking up on the project to see how the D version had progressed and was surprised to learn that, as of September 4th, ShortHike has gone open source. The code is released under the Apache 2.0 License. You can browse the source online at the ShortHike developer’s page and read more about the open source release in the ShortHike forums.