بازی Snake

حالا برایتان برنامه بازی اسنیک را می گذارم: 

uses graph,crt;
var
a,b,y,v,n,vy,e,f,g,h,r,t,s,m,z,i,goal:integer;
u,q,w:integer;
ali,sir,d,war:char;
begin
initgraph(a,b,'');

y:=320;
v:=1;
n:=240;
vy:=1;
s:=10;

while (ali<>chr(27)) do
begin
if keypressed then ali:=readkey;
if(ali='a')then
begin
y:=y-5;
setcolor(black);
circle(y+5,n,s);
setcolor(white);
circle(y,n,s);

end;
if(ali='s')then
begin
n:=n+5;
setcolor(black);
circle(y,n-5,s);
setcolor(white);
circle(y,n,s);
end;
if(ali='d')then
begin
y:=y+5;
setcolor(black);
circle(y-5,n,s);
setcolor(white);
circle(y,n,s);
end;
if(ali='w')then
begin
n:=n-5;
setcolor(black);
circle(y,n+5,s);
setcolor(white);
circle(y,n,s);
end;
delay(20);
end;
end.