Gardine

It is a floating widget on a upper right cornet of a screen.

You swipe it left, but don't release a finger, and a list of recent apps will appear.

The most recent app is always on the top of a stack.

Then moving finger up or down you highlight a desired app you want to bring back to a foreground.

By releasing a finger a selected app will be restored.

On the first run Gardine will request an "Accessibility service" permission in order to track switch between applications and a permission to display as a floating widget above all other windows.