Earth

    1 REM earth
    5 GO SUB 1000
   10 PAPER 0: INK 7: BORDER 1: CLS 
   20 LET hp=0
   50 CLS : FOR f=1 TO 50: PLOT INK RND*3+4,255.5*RND,175.5*RND: NEXT f
   60 LET la=50: LET l=1: PRINT AT 21,0;"ALIENS";TAB 12;"PLAYER";TAB 24;"LASER"
   70 LET p=0: LET c=16: LET co=5
   80 GO SUB 504: LET l=0
   92 LET i=20: LET st=INT (RND*20)+5
   93 IF co=0 THEN GO TO 210
   95 PRINT AT i,st; INK 1;"\b"
  100 PRINT AT 1,c;" "
  110 LET c=c+(INKEY$="8" AND c<31)-(INKEY$="5" AND c>0)
  115 PRINT AT 1,c; INK 6;"\a"
  122 BEEP .005,c
  125 PRINT OVER 1;AT i,st; INK 5;"\b"
  131 LET i=i-1
  133 IF i=-1 THEN GO TO 500
  138 LET st=st+INT (RND*3)-1+(3 AND st<-30)-(3 AND st>30)
  140 PRINT OVER 1;AT i,st; INK 4;"\b"
  143 PRINT AT 21,19;p;" "
  145 IF i=1 AND st=c THEN PRINT AT 1,c; INK 5; FLASH 1;"\c": GO TO 200
  160 IF INKEY$="0" AND la>0 THEN LET la=la-1: PRINT AT 21,30;la: GO SUB 300
  165 IF la<10 THEN PRINT AT 21,31;" "
  170 GO TO 100
  200 FOR g=1 TO 30
  205 OUT 254,RND*255
  206 BEEP RND*.05,RND*24-12
  208 NEXT g
  210 IF p>hp THEN LET hp=p
  221 PRINT AT 21,0
  222 INPUT ;"Your Score=";(p)''"Hi'Score=";(hp): PAUSE 500: GO TO 10
  224 GO TO 10
  300 PLOT INVERSE 1,c*8+3,159
  305 DRAW INK 5,0,-117
  308 BEEP .05,12
  309 PLOT INVERSE 1,c*8+3,159
  310 DRAW OVER 1,0,-117
  320 IF (i<17 AND i>1) AND st=c THEN LET p=p+100: LET la=la+1: PRINT AT 21,30;la: BEEP .1,2: PRINT OVER 1;AT i,c; INK 2;"\c": BEEP .2,3: PRINT OVER 1;AT i,c; INK 5;"\c": BEEP .1,4: PRINT AT i,c;" ": GO TO 85
  340 RETURN 
  500 LET p=p-50: LET co=co-1
  503 PRINT AT 21,19;" "
  504 FOR f=1 TO 5
  505 IF f<co THEN PRINT AT 21,6+f; INK 4;"\b"
  506 IF f>co THEN PRINT AT 21,5+f;" "
  510 NEXT f: IF l=1 THEN RETURN 
  520 GO TO 90
 1003 FOR f=0 TO 7: READ n,m,o: POKE USR "\b"+f,n: POKE USR "\a"+f,m: POKE USR "\c"+f,o
 1004 NEXT f
 1005 DATA 16,165,165,16,189,24,56,255,165,124,255,90,186,126,90,254,36,165,254,60,24,170,24,165
 1010 RETURN 
 9999 SAVE "earth" LINE 1: BEEP 1,32