The end is nigh finally. Bruce Willis' sci-fi twitch game, Apocalypse, due in stores Nov. 23, was supposed to come out in the fall. Of 1997. Originally, Willis' role was that of a computer-controlled ''virtual buddy'' who doles out sardonic advice and the occasional laser blast to help you escape from an Orwellian prison. But programming an artificial intelligence to follow players around turned out to be a particularly hairy ordeal, and ''it was obvious in focus tests that kids wanted to be Willis,'' recalls Activision producer Dave Stohl. After deciding to put the player in control of the star's persona, the company performed major surgery on the ailing game, replacing the burned-out development team with an outside company, NeverSoft. Luckily, all the raw materials Willis provided at the start of the project 3-D scans of his face and body, plus voice-overs could be salvaged, negating the need to call him back for more work. A smart move, considering one of his exclamations during the game is ''I'm not gettin' paid enough to do this crap!''