The Keep on the Borderlands is a "Dungeons & Dragons" module by Gary Gygax, first printed in December 1979.
 In it, player characters are based at a keep and investigate a nearby series of caves that are filled with a variety of monsters.
 It was designed to be used with the "Dungeons & Dragons Basic Set", and was included in the 1979–1982 editions of the "Basic Set".
 It was designed for people new to "Dungeons & Dragons".
The Dungeons & Dragons Basic Set is a set of rulebooks for the "Dungeons & Dragons" ("D&D") fantasy role-playing game.
 First published in 1977, it saw a handful of revisions and reprintings.
 The first edition was written by J. Eric Holmes based on Gary Gygax and Dave Arneson's original work.
 Later editions were edited by Tom Moldvay, Dave Cook, and Frank Mentzer.
The Dungeons & Dragons Basic Game is an introductory version of "Dungeons & Dragons" ("D&D") role-playing game packaged in the form of a board game.
 The original game was released in 2004 by Wizards of the Coast and was designed by Jonathan Tweet, one of the "D&D" 3rd edition designers.
 A new version of this game was released in September 2006.
Dwellers of the Forbidden City is an adventure module, or pre-packaged adventure booklet, ready for use by Dungeon Masters in the "Dungeons & Dragons" ("D&D") fantasy role-playing game.
 The adventure was first used as a module for tournament play at the 1980 Origins Game Fair, and was later published by TSR in 1981 for use with the first edition "Advanced Dungeons & Dragons" rules.
 The module was written by game designer David "Zeb" Cook, who partly ascribes his hiring by TSR to his work on this module.
 In the adventure, the characters are hired to find an object taken to a lost oriental-style city, which has been taken over by a cult of snake-worshipers, the yuan-ti, and their servants, the mongrelmen and tasloi.
 The module was ranked as the 13th greatest "Dungeons & Dragons" adventure of all time by "Dungeon" magazine for the 30th anniversary of the "Dungeons & Dragons" game in 2004.
David Lance "Dave" Arneson (October 1, 1947 – April 7, 2009) was an American game designer best known for co-developing the first published role-playing game (RPG), "Dungeons & Dragons", with Gary Gygax, in the early 1970s.
 Arneson's early work was fundamental to the development of the genre, developing the concept of the RPG using devices now considered to be archetypical, such as adventuring in "dungeons" and using a neutral judge who doubles as the voice and consciousness of all other characters to develop the storyline.
The New Easy-to-Master Dungeons & Dragons Game is an introductory set for the "Dungeons & Dragons" fantasy role-playing game, published by TSR, Inc. in 1991.
 It was a replacement for the previous "Dungeons & Dragons Basic Set", serving to introduce new players to the game, using the rule set previously established.
The Lost City (B4) is a "Dungeons & Dragons" adventure module by Tom Moldvay.
 It was first published by TSR in 1982 and was designed as a stand-alone adventure for use with the "Dungeons & Dragons Basic Set".
 The working title for the module was "The Lost City of Cynidecia".
 Moldvay designed the module to give novice Dungeon Masters experience fleshing out adventures and is only partially complete.
 The module is described as a low-level scenario, in which the only hope of the player characters' survival can be found in a ruined city slowly rising out of the sands.
 The adventure is set inside a huge step pyramid, with the lower pyramid only sketched out and the city itself described with a list of the major areas and a map.
 The adventure’s main villain is Zargon, a giant one-eyed monster and his minions.
 The entire double pyramid, not including the city, contains over 100 rooms.
The Dungeons & Dragons Companion Set is an expansion boxed set for the "Dungeons & Dragons" ("D&D") fantasy role-playing game.
 It was first published in 1984 as an expansion to the "Dungeons & Dragons Basic Set".
Dungeons & Dragons Master Rules is an expansion boxed set for the "Dungeons & Dragons" ("D&D") fantasy role-playing game.
 It was first published in 1985 as an expansion to the "Basic Set".
Dungeons & Dragons Immortals Rules, written by Frank Mentzer, is a boxed set for the "Dungeons & Dragons" ("D&D") fantasy role-playing game first published by TSR in 1986 as an expansion to the "Basic Set".

Question: What is the name of the American game designer who co-developed Dungeons & Dragons Basic Set and who developed the concept of the RPG?
Answer: Dave Arneson