▁Civil ▁War ▁military ▁mini atures . ▁ ▁In ▁the ▁mid ▁ 1 9 9 0 s , ▁he ▁worked ▁on ▁the ▁play - by - mail ▁game ▁E lder L ords ▁( based ▁on ▁his ▁D & D ▁campaign ), ▁promoted ▁and ▁designed ▁advent ures ▁for ▁the ▁computer ▁game ▁E am on ▁advent ures , ▁created ▁and ▁program med ▁Radio ▁Hor se ▁Racing , ▁a ▁computer ized ▁horse ▁racing ▁simulation , ▁created ▁the ▁' rain bow ▁do oz i ' ▁cy ber ▁cre atur at ons ▁ ▁and ▁ref ined ▁several ▁artificial ▁intelligence ▁computer ▁games . ▁M aint ained ▁a ▁correspond ence ▁with ▁Gary ▁G yg ax ▁from ▁ 1 9 7 5 ▁until ▁Mr ▁G yg ax ' s ▁death ▁in ▁ 2 0 0 8 . ▁ ▁Cre ated ▁and ▁produced ▁" F o am ▁Wars " ▁g aming ▁system ▁as ▁well ▁as ▁" No ▁P aint ▁Arm ies " ▁using ▁" G ran ny ▁Gr ate ". ▁ ▁Kre bs ' s ▁Law ▁of ▁G aming ▁" The ▁one ▁rule , ▁to ▁rule ▁them ▁all , ▁is ▁to ▁have ▁fun ." ▁ ▁References ▁ ▁S ources ▁R PG ▁Encyclopedia ▁( G ) ▁ ▁Sw an , ▁Rick . ▁The ▁Complete ▁Guide ▁to ▁Ro le - Play ing ▁Games ▁( St ▁Martin ▁Press , ▁ 1 9 9 0 ). ▁ ▁Category : 1 9 4 9 ▁birth s ▁Category : Al br ight ▁College ▁al umn i ▁Category : American ▁game ▁design ers ▁Category : D unge ons ▁& ▁Drag