"When building scene tree in Phaser engine the sprites added as last are rendered on top. Unlike, for example, in Unity, you cannot change order of sprites with setting its z position. You can only set z property and sort sprites within one group.
You can try to achieve this with:
-
making two groups (walls and gems) and tween them. But, in such case all gems will be under or above walls, depending on groups order.
-
making one group with all the walls and gems, but to move them you will have to create 8 tweens.
There is third way which allows you to put all sprites in one group (like in 2.) and transform gems and walls at once (like in 1.)."