This is another of the low-budget Roger Corman sci-fi/monster classics.
The set-up is that a research team sent to a remote Pacific island has gone missing, so of course, a new team has to be sent! And then their plane explodes, so they can't leave!
There's a lot of suspense in the early part of the movie, as the scientists, technicians and soldiers explore the island. But of course, you saw the movie poster, you read the title, you know the Crab Monsters will eventually show up!
The bad news is that the giant crabs look ridiculous on screen, like rejects from a parade somewhere. The good news is that in the plot, they are much more than just crabs… in a creepy kind of way!
As the movie moves along, the characters are killed off one by one, and the island is gradually destroyed until the last three people are left on the last rocky bit – which is kind of a cool concept.
As is usual in these movies, the "science fiction" is actually science fantasy – it doesn't make sense but is entertaining.
Richard Garland (husband of Beverly Garland) does well as the hunky scientist. Pamela Duncan is quite good as the female scientist, and looks good in a swimsuit in a 1950s sort of way. Russell Johnson (later the 'Professor' on Gilligan's Island) is quite good as the rival love interest for Pamela's character, though some changes as the movie was edited left out explanatory dialogue and leaves him looking like a bit of a jerk. There are some fun character actors playing the other scientists.
Could You Game This?
Well, in the movie the crabs are almost invulnerable, which wouldn't make a fun tabletop game unless you make it an RPG. If you add more crabs and make them less powerful, then you could have a campaign…