You can configure Window 8.1 to automatically display the App view (instead of the Start Screen) each time you press the Windows key. To enable this feature:

Right-click on the Taskbar > Properties .

. Go to the Navigation tab.

tab. In the "Start screen" section, check "Show the Apps view automatically when I go to Start".

Click on OK to validate.

As from now, each time you tap on the Windows key, the App View will be displayed (instead of the StartScreen):

Note that: When you make a search in App view, Windows will search everywhere. If you want to restrict the search to apps only, simply uncheck: