I think you are looking in perspective at a digital render of a tower base that has 1x2 blue bricks on each side (1 wide) with a 2x2 lime brick in the center. It only appears to be 1/3-1/3-1/3, but is in fact 1/4-1/2-1/4. You can see this best if you zoom in on the base plate and look at how the studs line up with the lowest tier of the base.
You're right. They cheated.
This youtube video shows the Robot Lab from a different camera angle.
Here you can clearly see what looks like three 1x2 bricks on a 2x4 brick of the same width. Cheaters! Boo!
Alright. Let's cheat, too.
I also think there's some funny business going on there in that model, and in a few other models.
For fun, I built it in BrickLink Studio (or at-least, how I think it would be built, my answer here has the instructions) and rendered it from a couple of angles. While it didn't give me enough control over the camera to reproduce the perspective exactly, I ...