What is the best way to show a submenu at tile menu design like windows?

Recently, I design a tiles menu and it is in responsive view. Which means it will support desktop, tablet/iPad, and mobile devices. But I notice it is very hard to have a submenu on it. Can anyone please provide me some idea that I can have the best way to show the submenu on a tiles menu like Windows 10?

Here is the layout and top left is the logo.

I have tried the slide menu. But it doesn't provide me the best solution. Because if I clicked at the bottom left's tile, it will be a bit weird when the slide menu slides in from right edge. The second reason is, there is a big gap user has to move their mouse from left to right edge and select the options. Alos, because of the big gap issue, it makes the button and the active submenu lost connection.