Dearest reader, I have a mercurial mind that needs little prompting. So when a post such as this pops up - it does fizz like a fizzy thing wot goes fizz. (OK, I could think of nothing either clear or not insulting, or both)
Please read, there will be a test: https://www.youtube.com/watch?v=Y1IJWz8x8zA
We have:
An Island.
Army (not navy?), base.
Fishing village
Nasty crabby mutants or aliens
Meddling Doctor.
That sets the scene. It doesn't take much imagination to see that you can run this in virtually any time period. You might have to move the island away from the British Isles.
A year or so ago we had a formula: big games at Entoyment then smaller games on a Sunday. Lots have changed since then, but a small campaign split between larger and smaller games would seem ideal. "I need a live sample!"
This is my (immediate) list but the Bronze Age Mediterranean does call-----.
Circe's island with a Sea Peoples colony has a minor dispute with Poseidon? An Egyptian god?
Viking/Normans/Medievals who are probably not that popular with the locals. My Poole In Flames terrain would fit perfectly!
Age of Piracy. Pirates and/or soldiers get crabs!
Cold War. A listening station, possibly an old WW2 radar base. Air/sea rescue base? Nuclear or chemical waste contamination is the regular cause.
Ultra modern. I'm trying to think of an excuse. Could there have been an incident that provoked the restoration of an old base?
Crabs --
Here's your leader! https://www.alternative-armies.com/collections/monsters-and-creatures/products/vnt37-crustacean-monster-45mm-tall
Several candidates in the 28mm SF selection. I like the scorpion bug! https://www.irregularminiatures.co.uk/
Khurasan is the way to go for our American ex's. Love the Spork.
Bit out of the box here but -- https://brigademodels.co.uk/product/furoraptors-pack-of-4/
And Etsy! https://www.etsy.com/uk/listing/1615712557/10-3d-printed-resin-crabs-mudcrabs-for?ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=miniature+crabs+for+diorama&ref=sr_gallery-1-1&frs=1&loc=1&local_signal_search=1&content_source=276c2027e3c765bb830cc16dee92bdee25bba17f%253A1615712557&organic_search_click=1&logging_key=276c2027e3c765bb830cc16dee92bdee25bba17f%3A1615712557
An old favourite! https://www.pendraken.co.uk/fantasy-monsters-giant-worms-fan-mon25