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                       Prototype
                            Differences 
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                    The game name is not displayed on
                        the title screen 
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                    | The SKIP text is not on the title screen but you
                        can still skip levels with the number keys | 
                  
                  
                    Instead of the level skip text (SKIP#) this
                        prototype lists the control method instead
                        (STICK).  Pressing Shift-Control-T will enable the
                        Trak-Ball mode and change the text to TBALL.  This
                        was simplified to Control-T in the released version.
                        (Thanks to Kr0tki for figuring this out) 
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                    | The game lacks explosions
                        on the 'THE END' screen | 
                  
                  
                    | The score and high score stay the color of the
                        current wave on the 'THE END' screen instead of
                        reverting back to red | 
                  
                  
                    The game doesn't automatically go back to the
                        title screen after the game ends 
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                    | The red missile tips (on the first two waves)
                        are colored green | 
                  
                  
                    The option for the all Smart Missiles variation
                        doesn't exist yet 
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