I was considering this too, but I don't really think one wants to switch
   that off on a per-game base, if for nothing thatn to give all users of the
   game the same chances. The NO_PREVIEW is nony in there so this can be
   arranged.
   


if there is to be an environment variable, use precedence, and
create a `TETRIS' variable, that one may place command line
switches in.  eg, i could define my default level by setting
TETRIS to `-l 9'.