Zork

Zork is a 1980s text-adventure computer game.

In "The Irish Pub Formulation", Sheldon claims that he has found an emulator on the Internet, which lets him play games from old 80's. One of which is Zork. Based on a search in the Internet, Sheldon's might be playing with the emulator at Classic Zork Trilogy. 

Episodes

• In "The Hofstadter Isotope" (S2E20), Sheldon tells Leonard they will play the buggy beta version of Zork for Vintage Game Night, but Leonard goes to a bar with Howard instead.
• In "The Irish Pub Formulation" (S4E6), Sheldon plays Zork with an emulator.