VHS and DVD releases in the United States and Canada. Critical response On Rotten Tomatoes, the film has an approval rating of 40% based on five reviews, with an average rating of 4.80/10. From contemporary reviews, "Byro." of Variety stated that Plan Z in the film was an "appropriate idea for "Gammera", a film which can be rated as Grade Z" The review went on to note that the films script and acting was "thoroughly predictable and pedestrian level". From retrospective reviews, AllMovie gave the film a positive review complimenting its direction, special effects, and cinematography, stating, "All in all, Gammera the Invincible is a solidly-crafted, engaging monster mash - just make sure you see the original Japanese version". Keith Phipps from AV Club stated "Gamera finds the perfect intersection between silly and cool, looking both dangerous and ridiculous as he tromps around. He’s no Godzilla, but he’s got his own thing going on." Arnold T. Blumberg from IGN awarded the film 6 out of 10, stating, "Gamera retains a kitschy charm but it was an inauspicious debut for a beloved icon." James McCormick from Criterion Cast called the film "a wonderful slice of schlock that you can watch again and again and appreciate the workmanship and love put into every scene." Artist and filmmaker Tomio Sagisu (co-creator of Spectreman) claimed that Nagata stole the idea of Gamera from him. Sagisu was soliciting ideas for a kaiju television program to various studios in 1962, and screened a demo reel entitled The Colossal Turtle, which featured a stop-motion animated turtle monster that pulled its limbs, expelled flames, and took flight. Sagisu commented, "I screened my demo reel at Daiei and no matter what anybody may think, I'm sure they used this reference for Gamera." Years later, effects director Yonesaburo Tsukiji dismissed Sagisu's allegations and claimed that Masaichi Nagata's son, Hidemasa, conceived the idea for Gamera. Home media In 1987, Sandy Frank Film Syndication released the film on VHS as Gamera. This release featured a new English dub (separate from the 1966 American version) for the Japanese version and replaced the original soundtrack with a new score. Neptune Media released the original, unaltered Japanese version and the altered U.S. version on VHS in 1999. Alpha Video released a cropped public domain version of the U.S. version on DVD in 2003, along with other public domain Gamera films. In 2010, the Japanese version