horror book where a group of people go to an island and murdered

[Anya]

heyy i read this book between 2015 and 2019 i remember that they go to the island and somebody dies by injection, someone else by being hit in the head with a pipe, and somebody being pushed off a cliff.
The murderer only invited people who came first in competitions where he came second and he went passed a window in a skull mask at one point. It was mentioned sometime after the first death that there was no way of getting back until the boat comes back after a week.
I really appreciate any help thanks xx

[E222]

And then there were none by Agatha Christie has a similar premise apart from the competition part

[E222]

https://www.goodreads.com/list/show/1...

A list of books inspired by ‘And then there were none’

[Juels]

Maybe Death on Gokumon Island by Seishi Yokomizo?

[Nicole]

Shiver has some vaguely similar ideas, but is probably too far off to actually be your book.