'Deliverance' has such a primal, paranoid appeal that it’s been copied almost as much as 'Die Hard.'It was adapted for the action-adventure template in Southern Comfort, and in Rituals it’s treated as straight horror — although the acting (by Hal Holbrook and four other men probably better known in Canada) is much better than in most horror films. Holbrook and his doctor cronies (Robin Gammell, Ken James, Gary Reineke, and producer Lawrence Dane) are stalked by a mysterious killer while roughing it in the Canadian woods. The fun is in watching these civilized men of reason devolve into primitive, terrified warriors in the face of an invisible enemy who seems to be everywhere. The movie delivers a couple of hefty shocks, but it ends on a quasi-mystical note guaranteed to leave you going “Huh?”Still worth a rental if you enjoy this type of yarn.