Question about areas + main quest

[Yourname942]

Will the main quest bring me to all of the areas? Or will I have to explore on my own? Thanks.

[CursedPanther]

No it won't. Many of the side quests will be discovered through exploring.

[Yourname942]

I mean major areas like kefalonia, Phokis, etc

[FunkFrog]

Broadly speaking the main quests take you to Phokis, Kephallonia, Athens, Sparta, Korthin, Olympia, and a few islands, Naxos and Keos being the two primary ones, I believe. Most regions in the game have important side missions/main story related missions in them, that aren't really required to get the game's offical ending, but needed if you wanna sort of finish the story 100%.

[Yourname942]

Will the main story bring me to each region at some point? Or will I have to discover some by myself on the side?

[FunkFrog]

There's quite a few regions you're never directly sent to, yes. But the game is open-world, and allows you to pack your bags and head to any island/region you desire and just start exploring, meeting people, get missions, so on. The main story itself, will only bring you to the regions I mentioned above, with a few more, I imagine. And then the DLC related content that's out so far, will bring you to a few more regions.

[Yourname942]

So far I've been completing each region I come across via the main story before progressing the main story, but I didn't know if I should explore side areas first, or 100% each region I am brought to.

[FunkFrog]

You don't have to do that at all. It's certainly a choice of playstyle. You can complete them 100% and then move on, or just decide to wander off and explore some random, obscure region that you don't have a mission in yet. Entirely up to yourself. But there's a lot of regions you'll have to actively go to, as the main story won't take you there.