This is trash. Another failed specimen of the survival-game genre.
1. The story is poor and cheap: spear-wielding girls on an island being slaughtered.
2. The art is fine but not as realistic as Battle-Royale so each character is virtually indistinguishable.
3. There are not too many characters but there's virtually zero development and they died so quickly in chain.
4. I skipped the dialogs to look for at least some decent ecchi, but there's none.
It's a total fail.