Colossal Cave Adventure is a text-based adventure game, released in 1976 by developer Will Crowther for the PDP-10 mainframe computer. It was expanded upon in 1977 by Don Woods. In the game, the player explores a cave system rumored to be filled with treasure. wikipedia 
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This Colossal Cave Adventure is based on the original 1977 Crowther/Woods PDP-10 Fortran IV code for the classic 350 point game. The Javascript version here, ported by Xenoveritas, is as faithful as possible in both game play and internal structure. This, coupled with termlib, a video display terminal emulator in Javascript, brings an authentic 1977 Crowther/Woods experience to your Web browser. site github