The Ancient Greece of Assassin's Creed Odyssey is the biggest and most dynamic open world in franchise history, and the E3 demo is just a taste of what its hugely varied landscape has to offer. Set during the Peloponnesian War, an ancient conflict between Athens and Sparta that was a crucial turning point in Grecian history, the Greece of Odyssey is torn between democracy and tyranny, myth and science, order and chaos – and you'll play a crucial role in deciding its fate.

The E3 demo unfolds on the islands of Delos and Mykenos, two tiny slivers of a much larger game world. Mykenos is a land of rocky cliffs and pristine beaches, where smoky temples and painted statues loom over bustling towns, blurring the lines between myth and everyday life. It's also densely populated, lush, and packed with activity. Wolves wander the outskirts of town, Athenian soldiers have set up camps at strategic points, and a colossal statue of Artemis Agrotera towers over the island's tallest hill. (You can climb the hunting goddess' statue, too; the arrowhead it points at the sky doubles as a synchronization point.) The more strategically important Delos, meanwhile, is smaller and comparatively quiet, with only a few ruins and villages dotting its rocky landscape. As Delos is a holy sanctuary of the god Apollo, it's forbidden to spill blood there – but don't let that stop you from roughing up any enemy soldiers you encounter. Delos also has a huge, legendary bear stalking one of its beaches, so tread carefully unless you're confident you can kill it.

Exploration in Assassin's Creed Odyssey expands on what we saw in Assassin's Creed Origins, with its climb-anything approach, its AI-guided NPCs running on individual schedules, and its lists of objectives that appear whenever you visit an enemy camp or other point of interest. Two things are immediately, strikingly different about the new Grecian open world when compared with sandy Egypt, however: first, it's vividly colorful (on Mykenos and Delos, at least), with bright wildflowers and vibrant foliage that stands out against sun-bleached seaside cliffs and pristine beaches.

"It's such a beautiful world, and the rendition that our world team and art team did is marvelous," says Creative Director Jonathan Dumont. "You know why people lived there back then? Because it looked good!"

Another striking thing about Ancient Greece is that its terrain ranges from "hilly" to "just a big mountain." Towns are built on elevations, and most of the climbing opportunities come not from huge, ornate buildings (of which there are still plenty), but from cliffs and mountainsides, which dominate much of the Greek countryside. This reflects a real geography that, according to Game Director Scott Phillips, is one of the big reasons the Ancient Greeks were such capable seafarers.

"In Ancient Greece, most people didn't travel by foot – they would travel by boat when they wanted to get somewhere," says Phillips. "Because Greece is super-super-mountainous, it was much easier to go by boat."

While you're better at climbing than most Ancient Greeks probably were, you might also find that it's quicker to get around by grabbing a rowboat and hugging the shoreline, rather than navigating the rough terrain between you and your destination. For anything more substantial than a quick jaunt through the shallows, though, you'll want to take the helm of your ship – a trireme named for Adrestia, goddess of retribution – and head out into open water.

"It's probably the biggest world we've ever done," says Dumont, adding that it will feature seasonal changes as well as a day/night cycle. "It's a super-diversified world, so we have different biomes for our regions – and since we're using the Peloponnesian War as a backdrop, they are in conflict, so there's a big gameplay aspect to that. Looking at each region, we wanted you to picture them in a different way. Let's say if you go in the south, like Crete or places like that, it's very rugged, very rocky. If you go towards Delphi, more in the north, it's big forests. If you look at our E3 demo, it's beautiful white rocks and blue ocean. When you find someplace, it has a unique feeling to it."

Attendees at E3 2018 can discover that uniqueness by visiting us in South Hall, at booth #1623, and playing the demo for Assassin's Creed Odyssey. Assassin's Creed Odyssey will launch on October 5th for PS4, Xbox One, and PC; stay tuned for more updates.