I have been digging around lately for feature-length games with readily available source code. I really enjoy looking back over great source code and trying understand the underlying structure. Most recently I learned about Arx Fatalis, which is now being developed further by passionate hobby developers under the project name Arx Libertatis. I never even knew this game existed!
Arx Fatalis was originally developed by Arkane Studios, the developers for the more recently popular game Dishonored. I have been making my way through this game in amazement. I am a huge fan of the King’s Field series of game and Arx Fatalis seems to capture a lot of the feelings of isolation that are synonymous with the King’s Field series. The fact that this entire project is open source and under the GNU Version 3 license is just icing on the cake. If you have time, follow this video tutorial and get a version of the source code up and running for yourself! At the very least, get the game off Steam or GOG and enjoy this wondrous experience!