EMPIRE OF THE SUN - This sweeping epic, based on an autobiographical J.G. Ballard novel, is about a British boy who spends three years in a Japanese prison camp during World War II. The story is sincerely acted, and Steven Spielberg has directed it with great technical skill. He lacks the artistic maturity to explore such a tough historical subject, though. Ballard vividly describes the prison's conditions of starvation and disease. In the movie it's more like a badly run summer camp where no horror or danger is a match for boyish high spirits. Tom Stoppard wrote the screenplay, which gives little hint of his strong literary abilities. John Williams composed the exalting and exhilarating music. (Rated PG) FAT CITY - Reissue of John Huston's respected 1972 drama about two boxers, a has-been and a newcomer, neither of whom is very good at the sport. Stacy Keach and Jeff Bridges give quietly commanding performances, backed by a colorful supporting cast. Leonard Gardner wrote the screenplay. Meandering, yet always on target in its observations, this picture stands with ``Raging Bull'' and ``Rocky'' as one of the best modern films about prizefighting. (Rated PG) REPENTANCE - Directed by Soviet filmmaker Tenghiz Abuladze, this allegorical attack on Stalinism was banned in the USSR for two years before the new glasnost policy allowed its release. The plot hinges on a woman who won't allow a dead tyrant's corpse to rest in peace. Abuladze employs a wide range of styles and devices, from surrealism to brutality, in attacking the evils of authoritarian rule. The result is sometimes bitingly clever, other times murky and obscure, but always provocative. (Rated PG) THREE MEN AND A BABY - Mildly diverting farce about three carefree bachelors whose lives change when a baby drops into their laps. There's also a subplot about crooks hunting for a packet of missing drugs. The story and characters are borrowed wholesale from Coline Serreau's hit French comedy ``Three Men and a Cradle.'' Leonard Nimoy directed the remake, with none of the filmmaking flair he showed in his two ``Star Trek'' movies. (Rated PG) THROW MOMMA FROM THE TRAIN -Farce about an aspiring author who tries to enlist his creative-writing teacher in a plot to swap murders: Each man would kill a person who's driving the other one crazy. Danny DeVito directed and stars in this comic version of Hitchcock's classic ``Strangers on a Train.'' His performance is the best thing in the picture, which is often more loud and vulgar than its silly story requires. (Rated PG-13) WALKER - A deliberately outrageous, wildly original drama based on the real-life exploits of William Walker, an American who became the self-declared President of Nicaragua in the 1850s, backed by mercenary soldiers and bankrolled by no less a capitalist than Cornelius Vanderbilt. Directed by Alex Cox, who posits the absurdity of war by making the battle scenes absurdly harsh and violent. The language of the screenplay, by Rudy Wurlitzer, is no gentler. The production was shot on location in Nicaragua. (Rated R) RATINGS: Films with ratings other than G may contain varying degrees of vulgar language, nudity, sex, and violence.