Watch the Assassin's Creed IV launch trailer

Assassin's Creed IV: Black Flag is, despite its name, actually the sixth game in the Assassin's Creed series (not counting the mobile AC titles).

Black Flag has a weird position in the Assassin's Creed storyline: the modern-day gameplay is a sequel to ACIII, while the pirate-themed historical element is a prequel of sorts.

In the modern setting, you play as an Abstergo employee — the organisation that's been the antagonist of the previous games. In the historical setting, you're the pirate Edward Kenway, the grandfather of Connor from Assassin's Creed III.

We spoke with Black Flag game director Ashraf Ismail who said that he'd "been surprised" when people had expressed shock at the historical time periods not occurring in a linear fashion.

"It was funny to me because we'd never said that we'd been moving through time in just one direction, but people seemed to have expected it."

However, the modern setting doesn't seem as integral to the story as Desmond Miles and his team were in the other games. Ismail said that there's really only 25 minutes or so that you must spend in the Abstergo building, although there are about five hours of optional modern gameplay if you want to explore.

As you might expect from the Caribbean setting, sea exploration forms a big part of the game, with naval combat a key gameplay mechanic. In fact, the Jackdaw, Kenway's ship, feels practically like a character more than a vessel.

"We wanted to get that feeling of exploring the seas just right," said Ismail. "Allowing players to feel like their ship was progressing and developing with them was part of that, so upgrading parts of the Jackdaw is an important part of the game."

Even more than other games in the series, ACIV wants to give you an open-world feeling: just head out, set sail in a random direction and explore the environment. Certainly, from what we've seen, the game world does looks impressive — lush tropical islands, beautifully designed settlements and the feeling of isolation on the high seas — but we'll wait and see if the new setting adds anything genuinely fresh to the combat and story-based missions.

Assassin's Creed IV: Black Flag is out on 29 October for current generation consoles and 21 November for PC, Xbox One and PS4.