$mw->bind('<Key>', [ sub {
        my $curshot=0 if 0;       # NEW

# Later in that code block...

        elsif ($_[1] == $Sprite::keycode::fire ) {
                return if $curshot>3;                 #NEW
                $curshot++;                           #NEW
                my $gun=new Sprite($c);
                $gun->image($img{"missle.gif"});
                $gun->names("missle","weapon");
                $gun->place($t::x, $t::y);
                push(@missles, {
                        direction => -1,
                        callback => sub {$curshot--}, #NEW
                        sprite => $gun,
                        });
        }