+............................................................................
+
+Great care has been taken to preserve 2.5's exact gameplay as intended
+by Don. We have added a "version" command.
+
+However, under the hood Open Adventure is rather different from 2.5.
+Where 2.5 was written in FORTRAN mechanically translated into
+extremely ugly C, Open Adventure has been translated into much more
+modern and idiomatic C. The extremely cryptic and opaque format of
+the original database of rooms, objects, and strings has been moved to
+YAML; this makes the brilliant design of it much easier to comprehend.
+
+== Earlier non-influences ==
+
+There is record of one earlier dungeon-crawling game called "dnd",
+written in 1974-75 on the PLATO system at University of Illinois
+<<DND>>. This was in some ways similar to later roguelike games but
+not to Adventure. The designers of later roguelikes frequently cite
+Adventure as an influence, but not dnd; like PLATO itself, dnd seems
+not to have become known outside of its own user community until
+rediscovered by computer historians many years after Adventure
+shipped.
+
+There was also Hunt The Wumpus <<WUMPUS>>, written by Gregory Yob in
+1972. There is no evidence that Yob's original (circulated
+in BASIC among microcomputer enthusiasts) was known to the ARPANET-
+and minicomputer-centered culture Crowther and Woods were part of
+until well after Adventure was written.
+
+(I was a developer of the Nethack roguelike early in that game's
+history, in the late 1980s; we knew nothing of PLATO dnd. We did know
+of Hunt The Wumpus then from its early Unix port, but it didn't
+influence us either, nor in any apparent way the designers of other
+early roguelikes. After my time the wumpus was included as a monster
+in Nethack, but this was done in a spirit of conscious museumization
+well after historians rediscovered Yob's game.)
+
+Neither of these games used an attempt at a natural-language parser
+even as primitive as Adventure's.