Zork
Three of the original Zork programmers joined with others to found Infocom in 1979. That company adapted Zork into Zork I-III, a trilogy of games for most popular small computers of the era. Personal Software published what would become the first part of the trilogy under the name Zork when it was first released in 1980, but Infocom later handled the distribution of that game and their later games. Part of the reason for splitting Zork into three different games was that, at the time, micros did not have enough memory and disk storage to handle the entirety of the original game. In the process, more content was added to Zork to make each game stand on its own.  A version of Zork I was issued as a hidden 'easter egg' in Call of Duty: Black Ops. It has exactly the same text and rules as the original.