>LOCAL
>DIM punta,a$
>LOCAL FN nuovacolonna(punta)                      '(Gcolonna$,Gpt)
>  SELECT PEEK(@a$+punta)
>    CASE _"1"
>      POKE @a$+punta,_"X"
>    CASE _"X"
>      POKE @Gcolonna$+punta,_"2"
>    CASE _"2"
>      LONG IF punta < 13
>        POKE @Gcolonna$+punta,_"1"
>        INC(punta)
>        FN nuovacolonna(punta)
>      END IF
>  END SELECT
>END FN
>
>Pizza, Pizza,
>
>-STAZ   ~)~

Unless I'm completely confused, there must be a wrong variable in here. 
Alessandro has probably already discovered it, but shouldn't this read,

LOCAL FN nuovacolonna(punta)                      '(Gcolonna$,Gpt)
  SELECT PEEK(@Gcolonna$+punta)
    CASE _"1"
      POKE @Gcolonna$+punta,_"X"
    CASE _"X"
      POKE @Gcolonna$+punta,_"2"
    CASE _"2"
      LONG IF punta < 13
        POKE @Gcolonna$+punta,_"1"
        INC(punta)
        FN nuovacolonna(punta)
      END IF
  END SELECT
END FN

Hey, it's just proof that it really does happen to the _best_ of us. 
Still an elegant bit of code.

 @^@
 =J= a  y