Solarbabies (1986)

In a sun-scorched post-apocalyptic world largely bereft of water, a group of youthful orphans, including Jason (Jason Patric) and Terra (Jami Gertz), spend their time playing a hard-hitting hockey-like game and defying an authority known as "the Protectorate." When Daniel (Lukas Haas), one of the younger orphans, discovers a strange sphere, it leads to a struggle between good and evil after the scheming Darstar (Adrian Pasdar) swipes the powerful orb.