I running OS X El Capitan version 10.11.2 on a mac with 14 gigs of memory, 2.7 GHz Intel Core i5 proccesor, AMD Radeon HD 6770m 512 MB graphics on 27 inch iMac. None of the games that i download here work and say "The application "<name of game>" can't be opened."

This has happened for games that are listed under OS X catergory. This has happened with every game here except Tube Tycoon.

it's probably because you have some sort of blocker in your settings or your java isn't sufficient

Recent versions of macOS / OS X tend to block applications downloaded from the internet from being open.

Downloading games using the itch app — https://itch.io/app — should fix this issue (among others). And the itch app is signed, so OS X will let you open it ;)