Thirteen fantasy-charged grippers, three rather memorable -- ""Roller Ball Murder,"" ""The Arsons of Desire"" and ""Nirvana, Gotterdammerung, and the Shot Put."" With Playboy, Esquire credits, it's no surprise that Harrison's stories are also fresh, timely, appealing, uncliche, even distinguished and lyrical, while still being tailored for the mass image. ""Roller Ball Murder"" is a terrifically murderous game played at ""brute speed"" (in the next century) with a 20-pound ball hurtling at 300 m.p.h. around an oval track and killing less lucky players. The game's getting harder to come out of alive -- the new rules working toward absolute obliteration of all players. In ""The Arsons of Desire"" a fireman trying to save naked women finds himself locked in sexual embraces in room after burning room -- a kinky tale. Most charming is the mystical shot-putter in ""Nirvana, etc."" who falls madly in love with his iron ball and can't stop throwing it night and day. Imaginative entertainment.