Since it is a 3D game, playing Tunnel Rush makes you feel as if you are truly within the tunnels. In addition to that, the tunnels are switching from being black and white to whirling in rainbow hues in a revolving pattern. Because of these changes, it is difficult to concentrate, and as a result, you need to concentrate more on avoiding the oncoming red obstacles and less on the twisting caverns.
There is a clear progression from one tunnel to the next, but keep in mind that they are designed to represent levels. A new level begins whenever there is a significant shift in the hues, textures, and perils of the tunnel.