Kids can be awful. In I Declare War, that petulance is displayed in various ways among a group of youngsters engaging in an afternoonlong session of Capture the Flag. The war game is accentuated by real weapons. Well, in the kids’ imaginations and on screen they’re real, but this isn’t The Hunger Games and no adolescents were harmed in the making of this picture. So, a kid picks up a tree branch and it becomes a bazooka, that kind of thing. The message behind that seems to be that we’ve desensitized violence or war is wrong or just that kids have vivid imaginations. Take your pick; there’s plenty of evidence to support any of those positions. Canadian filmmakers Jason Lapeyre and Robert Wilson have made a film that’s more worth talking about than actually seeing, because it’s a great conversation piece. But as a movie? It hovers around serviceable.