That said, if everything is 2d facing the camera then you could still use the perspective camera and adjust the size and position of the objects with different z so they are visually unmoving. Even some 3d stuff can be distorted to look unchanged.
edit:
Here's how:
Set camera to Perspective, and add the 3dcamera object to your project.
Then any object you to undo the perspective scaling to add three instance variables: xx, yy, and s.
Start of layout:
-- sprite: set xx to self.x
-- sprite: set yy to self.y
every tick
-- sprite: set s to 1-Self.Z/3DCamera.DefaultCameraZ
-- sprite: set scale to self.s
-- sprite: set x to (Self.xx-scrollx)*Self.s+scrollx
-- sprite: set y to (Self.yy-scrolly)*Self.s+scrolly
or if you want to use arbitrary sized sprites:
Start of layout:
-- sprite: set xx to self.x
-- sprite: set yy to self.y
-- sprite: set ww to self.width
-- sprite: set hh to self.height
every tick
-- sprite: set s to 1-Self.Z/3DCamera.DefaultCameraZ
-- sprite: set size to (self.ww*self.s, self.hh*self.s)
-- sprite: set x to (Self.xx-scrollx)*Self.s+scrollx
-- sprite: set y to (Self.yy-scrolly)*Self.s+scrolly
You just need to update xx and yy whenever you move the sprite.