Following lines, detecting colors, responding to light. It is still far from "seeing", but the LEGO Mindstorms EV3 & NXT sensors could be very useful when used properly.
The telephone game played with LEGO Mindstorms EV3 robots relies on the Color Sensors and the detection of colors. Sometimes the robots won't work. They could be influenced by a number of factors like the position of the sensor and the lighting in the room. This tutorial is a demonstration on how to account for and resolve this issue.
The Telephone game is played with 2 or more robots and is extremely funny. Each robot has a color wheel that can be rotated through the medium motor and a color sensor. The first robot on the left rotates the color wheel to a random color. The second robot must detect the color on the wheel and rotate its color wheel to this color. The third detects the color wheel of the second and so on.
It is described in details in Lesson 4 of Level C2. Cooperation