Cmd+Tab does not work on hidden or minimized windows
This one is a bit tricky :

press ⌘ Cmd + ⇥ Tab to show your running apps. Keep holding ⌘ Cmd.

press ⇥ Tab until you've selected the app

press the ⌥ Option, and let go of the ⌘ Cmd. 
( You must release ⌘ Cmd after pressing ⌥ Option ! )
( You must release ⌘ Cmd before release ⌥ Option ! )