CLicking on the game icon to play, open a black window and wont load anything else!

I even uninstalled the game, loaded it back again, same problem.

I click on the League of Legend icon on my computer, it create a fill black window and its stuck there.

Ironicly, while the game was loading the content, I had access to a loading screen and could, partly enter my account... but the only thing I had access was discount skins we all get from that promotion. Whats its call... 30 to 70% off random skins?

Once its finished loading, I couldnt do anything so I close the game, tried to reload it... AND IT DID THE SAME THING! A black screen!

Im not sure if its related but Im on a Mac. Is the PC version not doing this?