The floor and the player are sprites, the turning blocks are models placed in the 2D world (follow2d). The view in the corner sees both, through its own 2D camera and a 3D one that follows it, drawn in the same order as on the screen; the frame of what the screen shows is drawn by the view itself, on top, and only there.
Click the view and the player goes there (viewToWorld; for a view in perspective, viewToRay).
Click the preview first so it hears the keyboard. The arrows move.