“Be More Chill” is a new sci-fi, pop-rock, satirical allegory of a musical for tweens and early teens, and probably not anyone else.  Based on a 2004 novel about a high school loser who swallows a pill-sized computer that makes him cool, the show is well-staged and performed, but remains an emotionally disengaging experience.  Willed into production re-existence on the strength of its international, online teenage fanbase, expect to be hearing about it for some time to come.