The objects are just moving in a circle. Instead of the circle being on xy it's on xz and the z is used to scale the sprites for perspective.
Anywho the example is old. Here is one that just rotates the points around with more trig.
https://www.dropbox.com/s/zg21utl9iucey ... .capx?dl=1
And here's one where you can more artistically by just arranging the corners of a quad the circle will be on.
https://www.dropbox.com/s/nixq48nn85w3i ... .capx?dl=1
There are likely many other ways. For example you could avoid trig directly and use "move at angle" instead. Add two instance variables z and r2
global radius = 100
--- add 100*dt to rotY
--- sprite: set position to (0, 0)
--- sprite: move radius pixels at self.iid*360/sprite.count+rotY degrees
--- sprite: set r2 to self.x
--- sprite: set z to self.y/radius - 3
--- sprite: set position to (320, 240)
--- sprite: move self.r2/self.z pixels at rotZ degrees
--- sprite: set scale to -1/self.z
There are probably others