Fabien Sanglard spent a lot of time reading the source code of Duke Nukem 3D. Here his impressions.
Duke Nukem 3D Code Review
Since I left my job at Amazon I have spent a lot of time reading great source code. Having exhausted the insanely good idSoftware pool, the next thing to read was one of the greatest game of all time : Duke Nukem 3D and the engine powering it named "Build".
It turned out to be a difficult experience: The engine delivered great value and ranked high in terms of speed, stability and memory consumption but my enthousiasm met a source code controversial in terms of organization, best practices and comments/documentation. This reading session taught me a lot about code legacy and what helps a software live long.
As usual I cleaned up my notes into an article. I hope it will inspire some of us to read more source code and become better engineers.
Duke Nukem 3D Code Review