i=0;//x
j=0;//y
map[0,0]=0;
for (i=0; i<100; i+=1)
for (j=0; j<100; j+=1){map[i,j]=0;}

ii=0;
jj=0;
dir=0;
size=2000
for (seeds=0;seeds<4;seeds+=1)
{
ii=irandom(100);
jj=irandom(100);
for (s=0;s<size;s+=1)
  {
  map[ii,jj]=1
  dir=irandom(3)
  if (dir=0) {ii+=1};
  if (dir=1) {ii-=1};
  if (dir=2) {jj+=1};
  if (dir=3) {jj-=1};
  if (ii>100)or(ii<0)or(jj>100)or(jj<0)
  then {ii=irandom(100);jj=irandom(100);}
  }
}
for (i=0; i<100; i+=1)
for (j=0; j<100; j+=1){if map[i,j]=0 then instance_create(obj_wall,i*16,j*16)
                       if map[i,j]=1 instance_create(obj_hole,i*16,j*16)}