Question: How long was the male co-writer of "Pools of Darkness" employed by TSR, Inc? 

Context paragraphs:
Rakshan River: The Rakshan River (Urdu: دریائے رخشن‎ ) rises at the Nidoki pass, south-west of Shireza, district Washuk, Balochistan, Pakistan.  Under the name of Nag, and running south-westward, it unites with the lop stream at a point to west of Nag-e-Kalat.  It then flows west-south-west through the centre of the long valley comprising the Panjgur District, Makran, and parallel with the Siahan Range on the north and Zangi Lak hills on the south.  In Rakshan it possesses little or no water, in Panjgur, however, it expands into a series of bright clear pools (kor joh) connected with each other by small water channels running over a pebbly bed.  The banks are here bordered with numerous date palms and most of the water is used for irrigation.  To the west of Kallag, the last village in Panjgur is Dabbag, where there are more pools and much long grass, tamarisk and kahur trees in which wild pigs were to be found in the early 20th century.

Dragonlance: Dragonlance is a shared universe created by Laura and Tracy Hickman, and expanded by Tracy Hickman and Margaret Weis under the direction of TSR, Inc. into a series of fantasy novels.  The Hickmans conceived "Dragonlance" while driving in their car on the way to TSR for a job interview.  At TSR Tracy Hickman met Margaret Weis, his future writing partner, and they gathered a group of associates to play the "Dungeons & Dragons" role-playing game.  The adventures during that game inspired a series of gaming modules, a series of novels, licensed products such as board games, and lead miniature figures.

Jim Ward (game designer): James M. Ward (born May 23, 1951), is an American game designer and fantasy author.  He is most well known for his game development and writing work for TSR, Inc., where he worked for more than 20 years.

Ryton Pools Country Park: Ryton Pools Country Park is a country park one mile (1.6 km) south west of the village of Ryton on Dunsmore in Warwickshire, England.  The park occupies an area of about 100 acre and contains four pools, the largest of which covers approximately 10 acre .  Professional park rangers are employed to look after the varied flora and fauna of the park as well as the general maintenance of pathways and buildings.

Storytelling System: The Storytelling System is a role-playing game system created by White Wolf, Inc. for the Chronicles of Darkness (formerly known as the New World of Darkness), a game world with several pen and paper games tied in.  The Storytelling System is largely based on the Storyteller System, the rule set used for White Wolf's other, older game setting, the World of Darkness (for a time known as "old" or "classic" World of Darkness).

Alfréd Hajós National Swimming Stadium: The Alfréd Hajós National Swimming Stadium is an aquatics complex located on Margaret Island in Budapest, Hungary.  It was planned by and since 1975 bears the name of Alfréd Hajós, a renowned Hungarian swimmer and architect.  The facility has four floors and eight pools, including training pools, a diving pool and competitive swimming pools both for short course and long course.

Lorraine Williams: Lorraine Dille Williams is an American businesswoman.  She was hired as manager of TSR, Inc. by company co-founder Gary Gygax in 1984, and was in charge of the gaming company from 1986 to 1997.  Williams gained control of TSR the following year when the Blume brothers sold her their controlling shares of the company.  In 1996, an unexpectedly high cost of returned (unsold) fiction books and an expensive, unsuccessful foray into the collectible card game market caused a cash flow squeeze, and Williams was forced to sell TSR to Wizards of the Coast in 1997.

Pools of Darkness (novel): Pools of Darkness is a novel based on the "Pools of Darkness" computer role-playing game.  It was written by James Ward and Anne K. Brown, and published by TSR in February 1992.  The novel is set in the Forgotten Realms setting based on the "Dungeons & Dragons" fantasy role-playing game.  This book was the second in a trilogy, preceded by "Pool of Radiance" and followed by "Pool of Twilight".

Serpentine system: The serpentine system is a method employed in the organization of a competition to define the seeded teams and arrange them in pools.  The "n" ranked teams that will be involved in the tournament are distributed in "m" pools according to the following algorithm:

Frank Mentzer: Jacob Franklin "Frank" Mentzer III (born in 1950), is an American fantasy author and game designer best known for his work on early materials for the "Dungeons & Dragons" (D&D) fantasy role-playing game.  He was a performing folk musician from 1968 to 1975, and played one concert at the White House during the administration of Richard Nixon.  He was an employee of TSR, Inc. from 1980–1986, spending part of that time as Creative Advisor to the Chairman of the Board, Gary Gygax.  He also founded the Role-Playing Games Association (RPGA) during his time with TSR.  He has been closely involved with the world's largest game auction at the Gen Con game convention since 1983, and is an expert on, and a major collector of, family boardgames and role-playing games.  After Gygax was ousted from TSR at the end of 1985, Mentzer left TSR as well and helped him to start New Infinities Productions Inc. (NIPI).  When this venture failed, Mentzer left the gaming industry, eventually becoming the manager of a bakery.  In 2008, he closed down this business and, two years later, announced he was returning to the gaming industry as a founding partner of a new publishing company, Eldritch Enterprises.

Supporting paragraphs: Pools of Darkness (novel) Jim Ward (game designer)
Answer: more than 20 years