Telehack is a text-based simulation of an early version of the Internet.
Telehack is a virtual museum that allows one to see what the Internet was like in the 1980s, when young hackers were browsing through different bulletin board systems and shell accounts.
One can learn exactly how they hacked in a safe and simulated environment as well as view real documents saved from BBSes thanks to textfiles.com.
References
Telehack Wikipedia(Text) CC BY-SA