User blog comment:The.Outsider/Holiday!/@comment-5174994-20120816174606/@comment-5266147-20120817143437

some of the targets in past games have no weapons and are old men, ids say they were defensless.

That was the reason marked for the 18 rating on AC2 - Rev, AC1 didnt have the strong language but the multiple motiveless killing was replaced by extreme violence.

if you disagree with the rating you can complain, the Video Standards council are the administrators of pegi for 12, 15 and 18 ratings.