Case 1: Contact on one side.
Case 2: Contact on two sides.
Case 3: Contact on three sides.
Case 4: Contact on four sides, with a fairly large gap in the back.
Case 5: Contact on four sides, with a gap slightly larger than one figure in the back.
Case 6: Contact on four sides, completely surrounded.
In which of these cases does it seem that Orcs should not be able to run away or escape? And can you think of any other situations that might be tough or close judgement calls?