Gamera movies were scarce in Colorado. it didn't help that most of them didn't have the name "Gamera" in the title. I had seen half of War of the Monsters, about 3/4 of Attack of the Monsters and this, Destroy All Planets was the first one I saw all the way through.
I had no idea it was a Gamera movie, but since our hero makes his first appearance about 2 minutes into the movie I learned quickly.
as this was my third or so Gamera movie, I didn't mind all the stock footage of him fighting Barugon and Gyaos, since most of that was new to me as it was. now that I'm a bit older, I think it could have been trimmed down to a scene or two instead of 20 minutes of padding. it works OK though.
this was also one of the smarter alien monsters Gamera fought. and more vicious, though all of the titanic turtles foes made him bleed at some point. Viras invaded bodies of Earthlings (I think) and then when he needed them, lopped off their heads!
that was a surprising scene! he was also able to use his own body as a spear. Viras came to Earth because their race needed nitrogen to survive, and since our atmosphere is 78% nitrogen it seemed like it would do.