Guess The Number

NMax = 20
DO
  COLOR 15: CLS
  PRINT "Welome to Guess The Number"
  PRINT "written by sorceress"
  PRINT
  PRINT "Are you ready to play? (y/n)": INPUT a$
  IF a$ = "Y" OR a$ = "y" THEN GOSUB startgame
  IF a$ = "N" OR a$ = "n" THEN GOSUB endgame
LOOP

startgame:
RANDOMIZE TIMER
N = INT(RND * NMax + 1)
PRINT
PRINT "I have picked a number between 1 and"; NMax
g = 5
WHILE g > 0
  COLOR 7: PRINT "You have"; g; "guesses!"
  INPUT a$: M = VAL(a$)
  PRINT
  IF M < 1 OR M > NMax THEN
    COLOR 9
    PRINT "You must pick a number between 1 and 20."
  ELSE
    IF M < N THEN COLOR 6: PRINT "Your guess is too low!": g = g - 1
    IF M > N THEN COLOR 6: PRINT "Your guess is too big!": g = g - 1
    IF M = N THEN COLOR 10: PRINT "Yes, that is it! Well done :-)": SLEEP: RETURN
  END IF
WEND
COLOR 12: PRINT "Sorry, you are all out of guesses. My number was"; N
SLEEP
RETURN


endgame:
PRINT
PRINT "OK. Goodbye"
SLEEP
SYSTEM