Portal/Transmission Received

The newest achievement, added in March 1, 2010, requires the player to find one (or more in some larger stages) radio(s) in each level and bring it to specific points. A radio will have a red light on the front if it hasn't been brought to the correct location. The music will change to static as you approach the correct location, and then to a hidden signal when you have arrived, at which point the light will turn green. The light persists across saved games.

The hidden signal that is picked up may be a Morse code signal, or sounds similar to those found on modems. To get full benefit out of them, you need to use sound recording software, or otherwise extract the audio files from the game.