Fair enough, a great deal of last year's Assassin's Creed IV: Black Flag takes place on the sea, but some of the many islands you could explore on foot were pretty big. Nonetheless, the next instalment in the series, Assassin's Creed: Unity, will be even bigger, even though the whole game is set within a single city.
Whereas cities previously have been shrunk and otherwise altered in the series, Paris in Unity is supposedly to scale, at least as far as the famous monuments go:
"In previous Assassin's Creed games, when we did Rome and a bunch of other cities, they were a bit cheated in terms of scale, producer Lesley Phord-Toy told The Examiner. "In Paris, the monuments are done in 1:1 because you are able to go inside seamlessly with no loading, and so the actual size of Paris is larger than all of the landmass in Assassin's Creed IV: Black Flag".
Size isn't everything you might protest, and we tend to agree. A large game is not great on that merit alone. A great game that just happens to be large however, is an entirely different matter. Let's hope for the latter.