On windows 10, the one player script works well. Typical output:

C:\Users\tblaz\Documents\evelyn\to_phone>perl 8.board.pl
moves: 1  tiles: a e g o r t u
--------------------chosen: 0 56 outrage   score: 34
..........   0000000000
..........   0000000000
..........   0000000000
..........   0000000000
..........   0000000000
.outrage..   0111111100
..........   0000000000
..........   0000000000
..........   0000000000
..........   0000000000
moves: 2  tiles: x w m u c n e
--------------------chosen: 1 15 cowmen   score: 12
..........   0000000000
..........   0000000000
..........   0000000000
..........   0000000000
.c........   0100000000
.outrage..   0111111100
.w........   0100000000
.m........   0100000000
.e........   0100000000
.n........   0100000000

...

moves: 13  tiles: a e e f j p r
--------------------chosen: 0 77 eme   score: 14
..........   0000000000
...u......   0001000000
...n......   0001000000
..owl.....   0011100000
.c.iota...   0101131000
.outraged.   0111111110
.w.sec....   0101130000
eme..e....   1110010000
regilt....   1121210000
.nodi.....   0111100000
moves: 14  tiles: a a f j n p r
--------------------chosen: 0 100 nona   score: 13
..........   0000000000
...u......   0001000000
...n......   0001000000
..owl.....   0011100000
.c.iota...   0101131000
.outraged.   0111111110
.w.sec....   0101130000
eme..e....   1110010000
regilt....   1121210000
.nona.....   0112200000
moves: 15  tiles: a d f j p r v
--------------------chosen: 1 59 tared   score: 26

...


--------------------chosen: 0 22 kern   score: 10
..........   0000000000
..burp....   0011110000
kern......   1221000000
..owl.f...   0011101000
.c.iota...   0101131000
.outraved.   0111112110
.w.sepal..   0101151100
eme..e.o..   1110010100
regild.i..   1121220100
.nona..n..   0112200100
moves: 22  tiles: e g i j o y z
Terminating on signal SIGINT(2)

C:\Users\tblaz\Documents\evelyn\to_phone>
[download]

The source that produced this is:

#!/usr/bin/perl

use strict;    
use warnings;
use feature 'say';
use Path::Tiny;
use List::Util qw( shuffle uniq first sum );

my $n        = 10;    # configuration  board will be  $n by $n
my $maxtiles = 7;
my $dictionaryfile = path( "dict", 'enable1.txt' );
my $cachefilename = "words.11108138.$n";     # for caching subsets of 
+dictionary
my $n1            = $n + 1;
my $board         = ( '.' x $n . "\n" ) x $n;
my $heights       = $board =~ tr/./0/r;
my @dictwords;

if ( -f $cachefilename ) {
  @dictwords = split /\n/, path($cachefilename)->slurp;
}
else {
  print "caching words of max length $n\n";
  @dictwords = sort { length $b <=> length $a }
    grep /^[a-z]{2,$n}$/,
    split /\n/, path($dictionaryfile)->slurp;
  say "dict words are @dictwords";

  path($cachefilename)->spew( join "\n", @dictwords, '' );
}
my %isword = map +( $_, 1 ), @dictwords;

my @drawpile = shuffle +    #  thanks to GrandFather 11108145
  ('a') x 9, ('b') x 2, ('c') x 2, ('d') x 4, ('e') x 12, ('f') x 2,
  ('g') x 4, ('h') x 2, ('i') x 9, ('j') x 1, ('k') x 1,  ('l') x 4, (
+'m') x 2,
  ('n') x 6, ('o') x 8, ('p') x 2, ('q') x 1, ('r') x 6,  ('s') x 4, (
+'t') x 6,
  ('u') x 4, ('v') x 2, ('w') x 2, ('x') x 1, ('y') x 2,  ('z') x 1;

sub flip                    # transpose one of more grids
{
  map {
    ( local $_, my $flipped ) = ( $_, '' );
    $flipped .= "\n" while s/^./ $flipped .= $& ; '' /gem;
    $flipped
  } @_;
}

my @tiles = sort splice @drawpile, 0, $maxtiles;
print "moves: 1  tiles: @tiles\n";
my $pat = join '', map "$_?", @tiles;

my $word = first { /^[@tiles]+$/ and ( join '', sort split // ) =~ /^$
+pat$/ }
@dictwords;
$word or die "no starting word can be found\n";
my $pos = $n1 * ( $n >> 1 ) + ( $n - length($word) >> 1 );
substr $board,   $pos, length $word, $word;
substr $heights, $pos, length $word, 1 x length $word;
my $tiles = join '', @tiles;
$tiles =~ s/$_// for split //, $word;
@tiles = split //, $tiles;
push @tiles, splice @drawpile, 0, $maxtiles - @tiles;
my @chosen     = $word;
my $changed    = 1;
my $moves      = 1;
my $totalscore = ( length $word == $maxtiles ) * 20 + 2 * length $word
+;
print '-' x 20, "chosen: 0 $pos $word   score: $totalscore\n";
printboard();

while (@tiles) {
  $heights =~ tr/5// == $n**2 and last;   # all 5, no more play possib
+le
  my @best;                               # [ flip, pos, pat, old, hig
+hs, word ]
  my @all = ( @tiles, ' ', sort +uniq $board =~ /\w/g );
  $moves++;
  print "moves: $moves  tiles: @tiles\n";
  my @subdict = grep /^[@all]+$/, @dictwords;
  for my $flip ( 0, 1 ) {
    my @pat;
    $board =~ /(?<!\w).{2,}(?!\w)(?{ push @pat, [ $-[0], $& ] })(*FAIL
+)/;
    @pat = map expand($_), @pat;
    @pat = sort { length $b->[1] <=> length $a->[1] } @pat;

    for (@pat) {
      my ( $pos, $pat ) = @$_;
      my $old   = substr $board,   $pos, length $pat;
      my $highs = substr $heights, $pos, length $pat;
      my @under = $old =~ /\w/g;
      my $underpat = qr/[^@under@tiles]/;
      my @words    = grep {
             length $pat == length $_
          && !/$underpat/
          && /^$pat$/
          && ( ( $old ^ $_ ) !~ /^\0+\]$/ )    # adding just an 's' no
+t allowed
          && matchrule( $old, $highs, $_ )
          && crosswords( $pos, $_ )
      } @subdict;
      for my $word (@words) {
        my $score = score( $board, $heights, $pos, $old, $word );
        $score > $#best
          and $best[$score] //=
          [ $flip, $pos, $pat, $old, $highs, $word, $score ];
      }
    }
    ( $board, $heights ) = flip $board, $heights;
  }
  if ( $changed = @best ) {
    my ( $flip, $pos, $pat, $old, $highs, $word, $score ) = @{ $best[-
+1] };
    my $newmask = ( $old ^ $word ) =~ tr/\0/\xff/cr;
    $flip and ( $board, $heights ) = flip $board, $heights;
    substr $board, $pos, length $word, $word;
    substr $heights, $pos, length $highs,
      ( $highs & $newmask ) =~ tr/0-4/1-5/r | ( $highs & ~$newmask );
    $totalscore += $score;
    $flip and ( $board, $heights ) = flip $board, $heights;
    my $tiles = join '', @tiles;
    $tiles =~ s/$_// for split //, $word & $newmask;
    @tiles = split //, $tiles;
    print '-' x 20, "chosen: $flip $pos $word   score: $score\n";
    push @chosen, $word;
  }
  else {
    my $tiles = join '', @tiles;    # discard random tile
    $tiles =~ s/$_// and last for 'q', 'z', $tiles[ rand @tiles ];
    @tiles = split //, $tiles;
  }
  @tiles = sort @tiles, splice @drawpile, 0, $maxtiles - @tiles;
  $changed and printboard();
}
print "\nchosen words: @chosen\ntotalscore: $totalscore\n";

say "finishing\n";

# validate all words are in the dictionary
$isword{$&} or die "$& is not a word\n" while $board =~ /\w{2,}/g;
say "word is $&";
say "$board";
$board = flip $board;
$isword{$&} or die "$& is not a word\n" while $board =~ /\w{2,}/g;
say "word is $&";
say "$board";

sub crosswords {
  my ( $pos, $word ) = @_;
  my $revboard = '';
  local $_ = $board;
  substr( $_, $pos, length $word ) =~ tr//-/c;
  $revboard .= "\n" while s/^./ $revboard .= $& ; '' /gem;
  my @ch = split //, $word;
  while ( $revboard =~ /(\w*)-(\w*)/g ) {
    my $check = $1 . shift(@ch) . $2;
    length $check > 1 && !$isword{$check} and return 0;
  }
  return 1;
}

sub score {
  my ( $bd, $hi, $pos, $old, $word ) = @_;
  my $len  = length $word;
  my $mask = ( $old ^ $word ) =~ tr/\0/\xff/cr;
  substr $bd, $pos, $len, ( $old & ~$mask ) =~ tr/\0/-/r;
  my $highs = substr $hi, $pos, $len;
  substr $hi, $pos, $len,
    $highs = ( $highs & $mask ) =~ tr/0-4/1-5/r | ( $highs & ~$mask );
  my $score =
    ( $mask =~ tr/\xff// == $maxtiles ) * 20 + ( $highs =~ /^1+$/ + 1 
+) * sum
    split //, $highs;
  my ( $rbd, $rhi ) = flip $bd, $hi;
  my @ch = ( $mask & $word ) =~ /\w/g;

  while ( $rbd =~ /(\w*)-(\w*)/g )    # find each cross word of new ti
+le
  {
    my $rpos  = $-[0];
    my $rword = $1 . shift(@ch) . $2;
    length $rword > 1 or next;
    $highs = substr $rhi, $rpos, length $rword;
    $score += ( $highs =~ /^1+$/ + 1 ) * sum split //, $highs;
  }
  return $score;
}

sub printboard {
  my $bd = $board =~ tr/\n/-/r;
  $bd =~ s/-/   $_/ for $heights =~ /.*\n/g;
  print $bd;
}

sub matchrule {
  my ( $old, $highs, $word ) = @_;
  $old eq $word and return 0;
  my $newmask = ( $old ^ $word ) =~ tr/\0/\xff/cr;
  ( $newmask & $highs ) =~ tr/5// and return 0;
  my $tiles = "@tiles";
  $tiles =~ s/$_// or return 0 for ( $newmask & $word ) =~ /\w/g;
  return 1;
}

sub expand  # change patterns with several letters to several single l
+etter pats
{
  my @ans;
  my ( $pos, $pat ) = @{ shift() };
  push @ans, [ $pos, $` =~ tr//./cr . $& . $' =~ tr//./cr ] while $pat
+ =~ /\w/g;
  return @ans;
}
[download]

While this script has many similarities to what tybalt89 posted in his responses, this one differs primarily in how the path to the dictionary is specified. It seems to me that I needed to have everything I wanted to deploy to termux in one directory. So I created a 'dict' directory, and put the dictionary there. As this script matures, I hope to pull the functions out into a package that could be put in the same directory, which makes the directory 'dict' non-descriptive.

Q1) If I'm going to have one and only one subdirectory, what makes for a good name? lib, my_data, ?

Meanwhile, this exact script and architecture do not successfully get off the mark on my linux machine:

$ lsb_release -a
No LSB modules are available.
Distributor ID:    Ubuntu
Description:    Ubuntu 18.04.2 LTS
Release:    18.04
Codename:    bionic
$ perl 8.board.pl
moves: 1  tiles: a e e l o p w
no starting word can be found
$
[download]

If one looks at the output that I posted from the termux session, this is exactly what it does as well. What seems to happen is that @dictwords is populated only by the last item in the dictionary, which it cannot match, having two zz's. So that's a big head scratcher for me, which I'll state like this:

Q2) Why does this script show proper behavior on windows but bomb out on *nix systems?

Part of the questions I present with are about termux. I intend to use the same data to motivate a discussion on stack exchange for the less perly matters. my own opinion is that the topic of perl doesn't suffer much if the OT stuff doesn't go on and on. I will post a link to that discussion when that happens.

I did purchase a brand new game on amazon for 16 bucks. I do consider this a fair use, as I don't know how I could hustle money by becoming an Upwards shark. Here I scanned the rules.