+= A brief history of Colossal Cave Adventure =
+by Eric S. Raymond
+
+Adventure is the fons et origo of all later dungeon-crawling games,
+the grandaddy of interactive fiction, and one of the hallowed artifacts
+of hacker folklore.
+
+The very first version was released by Crowther in 1976, in FORTRAN on
+the PDP-10 at Bolt, Beranek, and Newman. (Crowther was at the time
+writing what we could now call firmware for the earliest ARPANET
+routers.) It was a maze game based on the Colossal Cave complex in
+Kentucky, lacking most of the D&D-like elements now associated with
+the game.
+
+Adventure as we now know it, the ancestor of all later versions, was
+was released on a PDP-10 at the Stanford AI Lab by Don Woods in 1977
+(some sources, apparently erroneously, say 1976). That version is
+sometimes known as 350-point Adventure.
+
+Between 1977 and 1995 Crowther and Woods themselves continued to work
+intermittently on the game. This main line of development culminated
+in the 1995 release of Adventure 2.5, also known as 430-point Adventure
+
+The earliest port to C was by Jim Gillogly under an early Unix running
+at the Rand Corporation in 1977; this version was later, and still is,
+included in the BSD Games collection. It was blessed by Crowther and
+Woods and briefly marketed in 1981 under the name "The Original
+Adventure".
+
+Many other people ported and extended the game in various directions.
+A notable version was the first game shipped for the IBM Personal
+Computer in 1981; this, for which neither Crowther nor Woods nor
+Gillogly were paid royalties, what "The Original" was competing
+against.
+
+The history of these non-mainline versions is complex and
+murky. Functional differences were generally marked by changes in the
+maximum score as people added puzzles and rooms; however, multiple
+ports of some versions existed - some in FORTRAN, some in C,
+some in other languages - so the maximum point score is not
+completely disambiguating.
+
+Same articles at <<DA>> are a narrative of the history of the
+game. There is an in-depth study of its origins at <<SN>>.
+Many versions are collected at The Interactive Fiction Archive
+<<IFA>>; note however that its dates for the earliest releases
+don't match other comments in the code or the careful reconstruction
+in <<SN>>.
+
+Future versions of this document may attempt to untangle some of the
+non-mainline history. For now, it will suffice to explain the chain of
+provenance that led from the original Adventure to the version
+distributed with this document.
+
+The original 350-point ADVENT on the PDP-10 had been one of my
+formative experiences as a fledgling hacker in 1976-77. Forty years
+later, in February 2017, while doing some casual research into the
+history of text adventure games, I looked through some source code at
+<<IFA>> and was delighted to learn of Adventure 2.5, a version of the
+Crowther-Woods mainline later than I had ever played.
+
+Adventure 2.5 had been shipped long enough ago that today's conventions of
+open-source licensing were not yet fully established. The Makefile
+contained a rights reservation by Don Woods and that was it.
+
+I wrote to Don asking permission to release 2.5 under 2-clause BSD;
+he replied on 15 May giving both permission and encouragement.
+
+Here is what Don said about differences between the original Adventure
+and 2.5:
+
+> The bulk of the points come from five new 16-point treasures. (I say "bulk"
+> because I think at least one of the scores included some padding and I may
+> have tweaked those.) Each of the new treasures requires solving a puzzle
+> that's definitely at the tricky end of the scale for Adventure. Much of the
+> new stuff involves trying new directions and/or finding new uses for stuff
+> that already existed; e.g. the forest outside is no longer a small number of
+> locations with partially random movement, but is a full-fledged maze, one
+> that I hope has a character different from either of the previous two.
+>
+> As the text itself says, V2.5 is essentially the same as V2, with a few more
+> hints. (I think I came up with a better one for the endgame, too.) I don't
+> seem to have a copy of the similar text from V2, so I don't know whether/how
+> it described itself to new and seasoned players.
+>
+> The other big change, as I mentioned above, was I added a way of docking
+> points at a certain number of turns. This was my second attempt to do what
+> the batteries had been for: require being efficient to achieve top score.
+> Alas, the batteries led to players deliberately turning the lamp off/on
+> whenever they weren't moving or were in a lit area, making the game take
+> even longer! I set the requirement at what felt like a hard but fair
+> number of turns, then applied several sneaky tricks to shave off another
+> twenty.
+>
+> I hacked up a wrapper around the game (still in Fortran, most likely, but
+> I forget) that would try each initializing the RNG using each second of a
+> given day, while feeding in a script that either worked or aborted early
+> if anything went wrong (such as a dwarf blocking my path). As I recall,
+> it took less than a day's worth of RNG seeds to find one that worked.
+>
+> I verified my script could work given a favorable RNG, and stuck
+> that number in the message.
+>
+> I like how that final puzzle, unlike the game itself, does not readily
+> succumb even given access to the game source. You really need to fit
+> together not only the goals and the map and use of inventory space, but
+> also details like just what _can_ you do in the dark...?
+
+== Nomenclature ==
+
+This project is called "Open Adventure" because it's not at all clear
+to number Adventure past 2.5 without misleading or causing
+collisions. Various of the non-mainline versions have claimed to be
+versions 3, 4, 5, 6, 7 and for all I know higher than that. It seems
+best just to start a new numbering series while acknowledging the
+links back.
+
+I have reverted to "Advent" for the binary to avoid a name collision
+with the BSD Games version.
+
+== Functional changes in Open Adventure ==
+
+A "seed" command has been added. This is not intended for human use
+but as a way for game logs to set the PRNG (pseudorandom-number generator) so
+that random events (dwarf & pirate appearances, the bird's magic word)
+will be reproducible.
+
+A -l command-line option has been added. When this is given (with a
+file path argument) each command entered will be logged to the
+specified file. Additionally, a generated "seed" command will be put
+early in the file capturing the randomized start state of the PRNG
+so that replays of the log will be reproducible.
+
+Using "seed" and -l, the distribution now includes a regression-test
+suite for the game. Any log captured with -l (and thus containing
+a "seed" command) will replay reliably, including random events.
+
+The adventure.text file is no longer required at runtime. Instead, it
+is compiled at build time to a source module containing C structures,
+which is then linked to the advent binary.
+
+== Sources ==
+
+[bibliography]
+
+- [[[IFA]]] http://rickadams.org/adventure/
+
+- [[[[DA]]] http://www.filfre.net/sitemap/
+
+- [[[SN]]] http://www.digitalhumanities.org/dhq/vol/1/2/000009/000009.html
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