From the Readme.txt file:
From Dragon User magazine, March 1984:Changes to this version:
* Fixed the irritating random freezing bug
* Game is now compatible with both CoCo and Dragon platforms
* Menu added to allow the player to choose colour set
* DragonDOS/Tandy Disk Extended Color BASIC compatible
* Game now restarts if reset button is pressed
* Press SPACE to start the game instead of joystick button
* CoCo and Dragon compatible pause/continue game feature
Use any of the following keys to pause the game:
ENTER, CLEAR, BREAK, SHIFT
Press SPACE to resume.
Whirlybird Run on YouTube by Marlin Lee.Whirlybird Run, from Dragon Data, involves piloting a helicopter over mountainous terrain, while destroying enemy rockets and bases with guns and bombs. As the game progresses, you enter a cavern that scrolls across the screen as you meet more dangerous opponents while avoiding running out of fuel. If this sounds familiar to you, it should do, as this is simply a rather good version of the arcade favourite Scramble. The number of machines Ieft, and the amount of fuel remaining, are shown at the top of the screen. One point always strikes me about this game - l can never grasp the logic that fills up your fuel tanks each time you bomb a fuel dump on the ground! in spite of this, and the fact that you seem to have a limitless supply of ammunition, the game is fun to play.
http://www.youtube.com/watch?v=xUKIpFRHbRM