I became interested in GL-117 back in 2014 when I found it performs well on modest LINUX hardware, making it a fun, very basic flight simulation game. I took a look at the source code and found it was pretty well organized, and clean enough to compile without modification on almost any of the popular LINUX desktop distros. I went to the primary web site and (and to their SourceForge archive) and tried to contact the developer to offer help with updates, but I never heard back from anybody. I began to play with the source code. I spent two and a half years making a substantial rewrite, and the result is now known as "Linux Air Combat" or simply "LAC". The graphical details are only slightly improved, but all other areas are vastly improved. For example, it now supports competitive, multiplayer Internet missions. The old arcade-style fight models have been completely rewritten so that now all of the aircraft fly properly according to the best available historic flight data. It also supports live interplayer voice communication with a powerful interface to the well-known "Mumble" VOIP package. I changed the focus to World War II, and at the time of this writing in May of 2018, LAC Version 6.03 supports 45 different aircraft. LAC is completely free and is published in open-source format. It's a great way for people to learn game programming in "C" and "C++", and it's a lot of fun. Learn all about it here: http://askmisterwizard.com/FlightSimMovies/LAC/LacIntroFullPage.htm or just do a google search for "Linux Air Combat". Many YouTube videos about LAC are also available through a YouTube search for "Linux Air Combat".