I don't know what it is, but this FM feels different from the rest without it being something outright different. The layout of the city, kinda split in the middle, plus the ambience of stumbling into a post-battle scene, will carve a space in your memories. Yes, it's a little keyhuntey at a little section, but there is a very detailed pdf walkthrough out there (just google it) and if it's a problem for you don't let it discourage you from an otherwise excelent mission