I really wish game companies would publish their old source for really out of date games. I really wish I could see what went into making the games I love like Fallout 1/2.
Jordan Mechner released the source of the 1989 Prince of Persia. https://github.com/jmechner/Prince-of-Persia-Apple-II
"Code review" http://www.fabiensanglard.net/prince_of_persia/index.php