[Question]
  [
As we learned from the IBM PC AT, [YouTube (see video)](https://www.youtube.com/watch?v=gffS40Djmxc), [Wikipedia (see article)](http://en.wikipedia.org/wiki/Beast_(video_game)), and Sesame Street:
# **The letter `H` is the *most merciless letter of the alphabet*!**
*(Even when actually composed from two elements in [Code Page 437](http://en.wikipedia.org/wiki/Code_page_437). In fact, it's even MORE merciless that way.)*
Like the Aliens in, uhm...er... *Aliens*, Beasts relentlessly pursue all who would dare come near their eggs. There is no reasoning with them. You must squash them if not to perish.
![A frightening encounter with the 4H Club](https://i.stack.imgur.com/MszXh.png)
For this scenario we will assume you're down to your last life, and you've met plain Beasts in a terrain with no eggs (as in the Wikipedia screenshot). You don't have a numeric keypad and can only move directly up/down/left/right...but the beasts apparently have one, and can move diagonally on their turn.
A Beast's choice of move among its options will be the one that minimizes distance from the player. If the distances are equal then tie breaking is done favoring left+up over right+down, but here's the disambiguation matrix to be explicit about it...lowest number to tie-break:
```
1 3 4
2 H 5
6 8 7
```
A beast never sleeps, but they are fortunately a bit slower than the player. They move *every other turn* (giving the player a head start by beginning their alternations on the second turn). They must move if a move is possible, regardless of if that takes them further from the player.
You crush a beast if you move a train of movable walls where it was sitting in a closed gap. These plain beasts are worth 2 points a head.
# Input
1. A pair of integers indicating a map's size in columns then rows.
2. Row count of lines of input, each of the column size...containing either a solid wall (`#`), a movable wall (`~`), a beast (`H`), the player (`O`) or just a space.
3. Input that will be either U, D, L, R indicating an *attempted* move by the player... or W to just wait. Note that attempting to push a movable wall which is blocked is legal input, it just will result in no action.
# Output
1. `aHHHH!` if the beasts killed the player...or nothing if the player won with no beasts remaining
2. The score
*(Note: For debugging purposes and/or amusement, you'll probably want to be able to output the state at each step; but that's too long to post here.)*
# Clarifications
* Maps are guaranteed to be bounded by solid walls.
* The order of who moves in a turn matters for the outcome. Thus: The player always goes first, then the beasts are given an ordering based on their *initial map position* if you were sweeping across the screen top to bottom left to right. *(A row 1 beast moves before a row 2 beast, and two beasts on the same row it would be the one with the lowest column number that would move before the other)*
* Diagonal moving beasts can move into any open adjacent diagonal space, regardless of if it requires squeezing between walls.
* A player can push any number of movable walls in a line provided that there's a space or a beast on the other end. But trying to push a train of walls into a Beast that is not pinned between walls treats the Beast as a wall, and won't allow the move.
* A Beast's move decision during a turn is based on the player's location at the *beginning* of the turn. Its desired optimization of "distance to player" is through an "as the crow flies" calculation. Any approximation which would give the same result as measured from the center of its square to the center of the player's square is fine.
* If a Beast can't make what would have been its first preferred move in a turn because a higher priority Beast took its spot, it will take its next best choice as opposed to staying in place (if a move is still possible).
# Sample Cases
### Simple Crush
*Input*
```
5 3
#####
#O~H#
#####
R
```
*Output*
```
2
```
### Preference Matrix -> Death
*Input*
```
5 5
#####
#O  #
# ~ #
#  H#
#####
WWDW
```
*Output*
```
aHHHH!
0
```
### Preference Matrix -> Win
*Input*
```
5 5
#####
#O  #
# ~ #
#  H#
#####
WRD
```
*Output*
```
2
```
### Waiting For the Reaper
*Input*
```
5 5
#####
#O  #
# ~ #
#  H#
#####
WWW
```
*Output*
```
aHHHH!
0
```
### Successful Defeat in the Wikipedia Scenario
*Input*
```
40 23
########################################
#~      ~ ~~  ~  ~ ~~   ~ ~~    ~ ~ ~~ #
#~~ ~          ~~   ~   ~ ~~         ~ #
#~# ~~   ~~~~      ~  ~~~~  ~    ~~~  ~#
# ~        ~   ~ ~~ #~~       ~        #
#~~  ~~~   ~ ~ ~      ~ ~~ ~  ~  ~  ~  #
#     ~~  ~  ~ ~ ~~~       H    ~  #~  #
#  O~  ~  #  ~~~ ~      ~ ~~  ~  ~ ~~  #
#       ~ ~H~~   ~~ ~ #        ~~   ~  #
# ~~         ~ ~~~  ~~   ~~~~      ~  ~#
#~  ~    ~~~  ~   ~        ~   ~ ~~  ~~#
#     ~      # ~ ~~  ~~~   ~ ~ ~ #    ~#
#~ ~ ~~  ~  ~   H     ~~  ~~ ~ ~ ~~~   #
#       ~   ~   ~   ~  ~     ~~~ ~     #
# ~~  ~  ~ ~~   ~       ~ ~ ~     ~    #
#      ~~   ~   ~  ~         ~      ~~ #
#~ ~     #    ~~~~  ~    ~~~H   # ~    #
#  ~   ~ ~   ~        ~          ~~  ~ #
#  ~   ~     #~  ~   ~~  ~  ~         ~#
# ~~ ~ ~  ~~                ~   ~      #
#    ~~~        ~ ~~  ~  ~  ~   ~      #
# ~ ~     ~            ~~   ~   ~  ~   #
########################################
RRRUWWWRRRURWWWWRDRRWWRDWWWWD
```
*Output*
```
8
```
Map provided by me, moves and output by @bobbel, corroborated by myself and @Allbeert.
# Winning Criteria
I think this is golfable, so I'll go with code golf rules unless people complain.
# Extra Credit
Playable Unicode implementation with the double-wide characters to resemble the image!
  
[Answer]
# Java, 1,843
My first try of solving this puzzle with Java.
I know, that there are a lot of improvements to make it shorter. But in the end it works for now.
To try it, you have to create a class `C` and paste the code.
`args[0]` (strictly speaking `a[0]`) is for input. The print method of the map is not included since it's not necessary for the puzzle output.
```
class C{static char                    [][]C;static int A=
0,B=0,D=0,E=0,F=0,G                    = 0 ; public static
void main(String[]a                    ){String []b= a[0].
split("\n");int c =                    Byte. decode(b [0].
split(" ")[1]); G=a                    [ 0 ] . replaceAll(
"[^H]","").length()                    ; String d = b [ b.
length - 1 ] ;C=new                    char[c][];for(int e
=1;e<b.length-1;e++                    ) C [ e - 1 ]=b[e].
toCharArray ( ) ; f                    ();boolean X= 0> 1;
for ( char  g : d .                    toCharArray ( ) ) {
switch(g){case 'U':                    h(0,-1);break; case
'D':h(0, 1); break;                    case 'L':h( -1, 0);
break;case'R':h(1,0                    );}if(X)i();X=!X;f(
);}System.out.print                    (D);}static void f(
){for(int a= 0;a<C.                    length;a++)for( int
b=0;b<C[a].length;b                    ++)if(C[a][b]=='O')
{A=b;B= a;}}static void h(int x,int y){E =x;F =y;switch(C[
B +y][A +x]){case 'H':g();break;case ' ':j(A,B);break;case
'~':k();}}static void i(){if(G<1){return;}int[][]l=new int
[G][];int m=0;for(int r=0;r<C.length;r++){for(int c=0;c<C[
r].length; c++){if(C[r][c]=='H'){l[m++]=new int[]{c,r};}}}
for(int[]n:l){o(n[0],n[1]);}} static void o(int a, int b){
int[]c=d (a,b);E=c[0];F =c[1];if(E !=0||F !=0){ j(a,b);} }
static int[]d(int a,int b){int[][]d={{1,3,4},{2,0,5},{6,8,
7},};int[]e=new int[]{0,0};double f=999;for(int r=-1;r<2;r
++){for(int c=-1;c<2;c++){if(C[b+r][a+c]==' '||C[b+r][a+c]
=='O'){int g=a+c-A;                    int h=b+r-B; double
i=Math.sqrt(g*g+h*h                    );if(i<f){e=new int
[]{ c,r};f =i;}else                    if(i==f){if(d[r+1][
c+1]<d[e[1]+1][e[0]                    +1]){e=new int[]{c,
r};}}} }}return e;}                    static void k(){if(
p(E,F,false)){q(E,F                    );} }static void q(
int x,int y){switch                    (C[B+y][A+x]){ case
'~':q(x+E,y+F);case                    'H':case ' ':j(A+x-
E,B+y- F);}} static                    boolean p(int x,int
y,boolean h){switch                    (C[B+y][ A+x]){case
' ':return !h; case                    '~':return h?h:p(x+
E,y +F, false);case                    'H':return h?!h:p(x
+E , y+ F, true) ;}                    return h&&C[B+y][A+
x] == '#' ; }static                    void j(int a,int b)
{char c=C[b][a];if(                    C[b+F][a+E]=='O'){g
();}else if(C[b+F][                    a+E]=='H'){D+=2;G--
;c=C[b][a];C[b][a]=                    ' ';}else{C[b][a]=C
[b+F][a+E];}C[b+F][                    a+E]=c;}static void
g () { System .out.                    print("aHHHH!\n"+D)
;     System      .                    exit  ( 0  ) ;  } }
```
---
To run it, try for example:
```
root@host:/cygdrive/c/workspace/project/bin> java C "5 5
> #####
> #O  #
> # ~ #
> #  H#
> #####
> WWDW"
aHHHH!
0
root@host:/cygdrive/c/workspace/project/bin>
```
---
Output of the last big scenario one turn before a beast eats the player:
```
████████████████████████████████████████████████████████████████████████████████
██▓▓            ▓▓  ▓▓▓▓    ▓▓    ▓▓  ▓▓▓▓      ▓▓  ▓▓▓▓        ▓▓  ▓▓  ▓▓▓▓  ██
██▓▓▓▓  ▓▓                    ▓▓▓▓      ▓▓      ▓▓  ▓▓▓▓                  ▓▓  ██
██▓▓██  ▓▓▓▓      ▓▓▓▓▓▓▓▓            ▓▓    ▓▓▓▓▓▓▓▓    ▓▓        ▓▓▓▓▓▓    ▓▓██
██  ▓▓                ▓▓      ▓▓  ▓▓▓▓  ██▓▓▓▓              ▓▓                ██
██▓▓▓▓    ▓▓▓▓▓▓      ▓▓  ▓▓  ▓▓            ▓▓  ▓▓▓▓  ▓▓    ▓▓    ▓▓    ▓▓    ██
██          ▓▓▓▓    ▓▓    ▓▓  ▓▓  ▓▓▓▓▓▓                        ▓▓    ██▓▓    ██
██          ▓▓▓▓    ██    ▓▓▓▓▓▓  ▓▓            ▓▓  ▓▓▓▓    ▓▓    ▓▓  ▓▓▓▓    ██
██              ▓▓  ▓▓  ▓▓▓▓      ▓▓▓▓  ▓▓  ██                ▓▓▓▓      ▓▓    ██
██  ▓▓▓▓                  ▓▓  ▓▓▓▓▓▓    ▓▓▓▓  ├┤  ▓▓▓▓▓▓▓▓            ▓▓    ▓▓██
██▓▓    ▓▓    ├┤◄►▓▓▓▓▓▓├┤  ▓▓      ▓▓                ▓▓      ▓▓  ▓▓▓▓    ▓▓▓▓██
██          ▓▓            ██  ▓▓  ▓▓▓▓    ▓▓▓▓▓▓      ▓▓  ▓▓  ▓▓  ██        ▓▓██
██▓▓  ▓▓  ▓▓▓▓    ▓▓    ▓▓                  ▓▓▓▓    ▓▓▓▓  ▓▓  ▓▓  ▓▓▓▓▓▓      ██
██              ▓▓      ▓▓      ▓▓      ▓▓    ▓▓├┤        ▓▓▓▓▓▓  ▓▓          ██
██  ▓▓▓▓    ▓▓    ▓▓  ▓▓▓▓      ▓▓              ▓▓  ▓▓  ▓▓          ▓▓        ██
██            ▓▓▓▓      ▓▓      ▓▓    ▓▓                  ▓▓            ▓▓▓▓  ██
██▓▓  ▓▓          ██        ▓▓▓▓▓▓▓▓    ▓▓        ▓▓▓▓▓▓        ██  ▓▓        ██
██    ▓▓      ▓▓  ▓▓      ▓▓                ▓▓                    ▓▓▓▓    ▓▓  ██
██    ▓▓      ▓▓          ██▓▓    ▓▓      ▓▓▓▓    ▓▓    ▓▓                  ▓▓██
██  ▓▓▓▓  ▓▓  ▓▓    ▓▓▓▓                                ▓▓      ▓▓            ██
██        ▓▓▓▓▓▓                ▓▓  ▓▓▓▓    ▓▓    ▓▓    ▓▓      ▓▓            ██
██  ▓▓  ▓▓          ▓▓                        ▓▓▓▓      ▓▓      ▓▓    ▓▓      ██
████████████████████████████████████████████████████████████████████████████████
```
Without silly line spaces: <http://pastebin.com/raw.php?i=QhpxKcCT>
So the players way is ending after the moves `RRDDDRRRWW`, because on the last `W`ait, the beast to the left will go to the right to eat the player.
---
Another example of the original big map but different moves:
<http://pastebin.com/raw.php?i=nBWjC3PZ>
See this animation: <http://youtu.be/0DIhEhjWd6s>
---
And the last example with original map and different moves (according to the new beast movement rules):
<http://pastebin.com/raw.php?i=NNmgzx7U>
See on youtube: <http://youtu.be/jXPzL88TU2A>
[Answer]
# C - ~~1004~~ ~~984~~ 917
Ahh, the beauty of C. Following the spirit of the other answer, I tried to format mine as well :)
I imagine there are still some improvements here and there, but this was really fun to write and golf. The character count includes all necessary spaces and new lines.
```
#define M(y,x,c) {t[y][x]=32;t[p][q]=c;y=p;x=q;}
   #define E {printf("aHHHH!\n%d",Z);exit(0);}
    #define A sqrt(pow(X-Q,2)+pow(Y-P,2))*30
           #define L (char)(m[s]>>8)
            #define G (char)(m[s])
             #define B(b) if(T==b)
              #define J M(Y,X,79)
               #define T t[P][Q]
r,c,X,Y,H,i,j,k,Z,p,q,P,Q,u,v,s,w,m[99],b[8]={
-1,255,65280,65281,1,511,257,256},t[999][999],
x[99],y[99];main(){char N[99];m[85]=b[2];m[68]
=256;m[76]=255; m[82]=1; scanf("%d %d",&c,&r);
for(;P<r;P++)                    for(Q=0;Q<c&&
scanf("%c",&T                    );T-10&&T-13?
Q++:Q){B(79){                    Y=P;X=Q;}B(72
){y[H]=P ;x[H                    ++]=Q;}}scanf
("%s",N);for(                    ;i<strlen(N);
i++){s=N[i];P                    =p=Y+L;Q=q=X+
G;B(32)J B('~')                  {while(P+=L,Q
+=G,T=='~');B                    (72){u=P+L;v=
Q+G;if(t[u][v]                   ==35||t[u][v]
=='~'){Z+=2;T=                   '~';J}}B(32){
T='~';J}}else                    B(72)E if(r=!r)
for(j=0;j<H;j                    ++){P=y[j];Q=
x[j];if(T-72)continue;v=A;s=0;for(k=0;k<8;k++)
{P=y[j]+(char)(b[k]>>8);Q=x[j]+(char)(b[k]);u=
A;B(32)if((c=v-u+99)>s){s=c;q=Q;p=P;}B(79)E}if
(s)M(y[j],x[j],72)}}printf("%d",Z);}//////////
```
I tested this with all the sample cases and a few more of mine, and it seems to be working properly. If anyone finds any situation in which it doesn't answer properly, please let me know.
Input is from stdin, and output to stdout. There are no checks for incorrect input. And, it returns the score if the player gets eaten, or if the player is alive after all movements are executed (even if there are still `H`'s around. 
Ungolfed version:
```
#define M(y,x,c) {t[y][x]=32;t[p][q]=c;y=p;x=q;}
#define E {printf("aHHHH!\n%d",Z);exit(0);}
#define A sqrt(pow(X-Q,2)+pow(Y-P,2))*30
#define L (char)(m[s]>>8)
#define G (char)(m[s])
#define B(b) if(T==b)
#define J M(Y,X,79)
#define T t[P][Q]
r, c, X, Y, H, i, j, k, Z, p, q, P, Q, u, v, s, w, m[99], b[8] = { -1, 255,
        65280, 65281, 1, 511, 257, 256 }, t[999][999], x[99], y[99];
main() {
    char N[99];
    m[85] = b[2];
    m[68] = 256;
    m[76] = 255;
    m[82] = 1;
    scanf("%d %d", &c, &r);
    for (; P < r; P++)
        for (Q = 0; Q < c && scanf("%c", &T);T-10&&T-13?Q++:Q) {
            B(79) {
                Y=P;
                X=Q;
            }
            B(72) {
                y[H]=P;
                x[H++]=Q;
            }
        }
    scanf("%s", N);
    for (; i < strlen(N); i++) {
        s = N[i];
        P = p = Y + L;
        Q = q = X + G;
        B(32)
            J
        B('~') {
            while (P += L, Q += G, T=='~');
            B(72) {
                u=P+L;
                v=Q+G;
                if(t[u][v]==35||t[u][v]=='~') {
                    Z+=2;
                    T='~';
                    J
                }
            }
            B(32) {
                T='~';
                J
            }
        } else B(72)E
        if (r = !r)
            for (j = 0; j < H; j++) {
                P = y[j];
                Q = x[j];
                if (T-72)
                continue;
                v = A;
                s = 0;
                for (k = 0; k < 8; k++) {
                    P = y[j] + (char) (b[k] >> 8);
                    Q = x[j] + (char) (b[k]);
                    u = A;
                    B(32)
                        if ((c = v - u + 99) > s) {
                            s = c;
                            q = Q;
                            p = P;
                        }
                    B(79)
                        E
                }
                if (s)
                    M(y[j], x[j], 72)
            }
    }
    printf("%d", Z);
}
```
[Answer]
# Perl 6: 741 characters, 758 bytes
The golfed version is at the bottom, since it's basically linenoise. Above it is my pre-golfed version. Both are interactive (they'll read as many commands from the input file as they can and then move on to using STDIN to get commands). They try to use the original characters and colors.
Usage is like `perl6 beast.p6 beast-input`:
```
use Term::ANSIColor;
class BeastGame {
    enum BeastParts <None Player Beast M-Wall S-Wall>;
    has @.board;
    has Int $.turn = 0;
    has Int $.score = 0;
    method indices (\matcher) {
        @.board.pairs.map: {
            .key*i X+ .value[].pairs.map: {
                .key if .value ~~ matcher
            }
        }
    }
    multi postcircumfix:<[ ]> (BeastGame \SELF, Complex \c) is rw { SELF.board[c.im][c.re] }
    has Complex $!player;
    method player { $!player = $.indices(Player)[0] }
    method Bool { so $.indices(Player) & $.indices(Beast) }
    method new (@lines) {
        my @board = @lines.map:
            {[ %(' ',<O H ~ #> Z=> None, Player, Beast, M-Wall, S-Wall){ .comb } ]}
        self.bless: :@board
    }
    method gist {
        state @symbol-map = map {colored .key, .value~' on_black'},
            ('  ',<◄► ├┤ ▒▒ ██> Z=> <default cyan red green yellow>);
        @.board.map({ @symbol-map[@$_].join }).join("\n")
    }
    method step ($d) {
        my $direction = %(:W(0), :L(-1+0i), :R(1+0i), :U(-1i), :D(1i)){$d};
        $direction // return self;
        self.move($.player,$direction);
        if ++$!turn %% 2 {
            for $.indices(Beast).eager -> $c {
                for (-1-1i,-1+0i,-1i,1-1i,1+0i,-1+1i,1+1i,1i,0i)\
                        .sort({abs $c + $^d - $!player})
                {
                    last if self.move($c, $_).defined;
                }
            }
        }
        self;
    }
    method move ($cur, $by) {
        return $cur if $by == 0;
        my $to = $cur + $by;
        my &cur-is  = { self[$cur] ~~ $^o }
        my &next-is = { self[$to]  ~~ $^o }
        return if cur-is S-Wall;
        (self[$to], self[$cur]) = (self[$cur], None)
            if next-is None
            # Move wall
            or cur-is Player | M-Wall and next-is M-Wall and self.move($to, $by)
            # Kill Player
            or cur-is Beast  and next-is Player
            # Squish Beast
            or cur-is M-Wall and next-is Beast  and self[$to+$by] ~~ M-Wall|S-Wall and $!score += 2
    }
}
my $width = get.words[1];
my $game  = BeastGame.new(lines[^$width]);
my @commands = '',lines.comb,{$*IN.get.comb}...*;
while $game {
    $game.step: @commands.shift;
    print "\e[2J";
    print "\e[H";
    say $game;
}
say "aHHHH!" unless $game.player;
say $game.score;
```
The golfed version:
```
my ($u,$s,$m)=0,0;my@b=lines[^get.words[1]].map:{[%(' ',<O H ~ #>Z=>^5){.comb}]}
my@a='',lines.comb,{$*IN.get.comb}...*;sub g(\c)is rw {@b[c.im][c.re]}
my&n=->\o{@b.kv.map:{$^k*i X+$^v[].kv.map:{$^l if $^w==o}}}
my&p={$m=n(1)[0]}
my&M=->$c,$b{my$t=$c+$b;my&c={$^o==g $c}
my&x={$^o==g $t}
c(4)??0!!$b??(($c,$t)».&g=(0,g $c)
if x(0)||c(1|3)&&x(3)&&M($t,$b)||c(2)&&x(1)||c(3)&&x(2)&&2 <g($t+$b)&&($s+=2))!!1}
while n(1)&n(2) {for 1
{M p,%(:W(0),:L(-1),:R(1),:U(-1i),:D(1i)){@a.shift}//last;if $u++%2
{for n(2).eager ->$c{last if M $c,$_
for(-1-1i,-1+0i,-1i,1-1i,1+0i,-1+1i,1+1i,1i,0i).sort({abs $c+$_-$m})}}}
say "\e[2J\e[H",join "\n",map {[~]
(map {"\e[$^v;40m$^k\e[0m"},'  ',<39 ◄► 36 ├┤ 31 ▒▒ 32 ██ 33>)[@$_]},@b}
say "aHHHH!" if !p;say $s;
```
Happy Easter!
]