This compressed file contains 9 text files that make up the entire source code for the original Metroid game for the NES. These files are an expansion of SnoBro’s Source code he posted a few years ago. The code has been changed to be assembled with Ophis instead of x816 because of memory issues. Labels corresponding to address values have been added to every line to make the code easier to follow for beginners interested in understanding the inner workings of a Nintendo game. The labels also make the code easier to debug if it is modified. At this time, the source code is still a work in progress but it is much farther along than the original document. The title page is completely documented. The intro routine, end routine, password scheme and sound engine are described in detail. About a third of the game engine is detailed and about half of each game area page.