Fascinating: Duke Nukem 3D Code Review

Silverman would write a new engine for 3D Realms but he would keep the source code. He would only deliver a binary static library (Engine.OBJ) with an Engine.h header file. The 3D Realms team on their side would take care of developing the Game module (Game.OBJ) and would also release the final executable DUKE3D.EXE.