Where a long shadow stretches far at 45 degrees, extruded text stacks a shadow tightly behind the letters — usually straight down — only as far as the desired thickness, so it reads as a solid block cut from stock. Darkening that side colour in steps sells a light source hitting it from an angle.
Adding perspective and a 3D rotateX/rotateY transform tilts the letters as if a real camera were looking at them, revealing more of that thickness.
When to use
Use for game titles, brutalist headlines, retro badge logos. Avoid body text — the thick shadow hurts legibility.