It's the end of an era for Naughty Dog, the video game studio behind the sorts of franchises you see trailers for at the movie theater. When "Uncharted 4: A Thief's End" comes out for the PlayStation 4 this May, it'll serve as a full resolution for a series that gamers have spent millions upon millions of dollars on since 2007.

Naughty Dog games are usually pretty special. The studio's previous release, "The Last Of Us," was hailed by the press as a masterpiece that told an original story about survival against unfathomable odds. Naughty Dog also created the cartoonish "Jak and Daxter" and "Crash Bandicoot" games -- adrenaline-fests that tap into a completely different part of the emotional spectrum.

The Huffington Post recently spoke with Bruce Straley, co-director of "Uncharted 4," about protagonist Nathan Drake, game design and why Naughty Dog decided this would be the last entry in the series.

﻿Nathan Drake is kind of the ultimate white, male protagonist. He's like a 21st-century Indiana Jones. But a lot of people are waking up to the need for more diverse characters and stories in our popular culture. Did you think about these issues at all for "Uncharted 4"?

Bruce Straley: The industry is changing and the world is changing -- all for the better. With "Uncharted 4," we're trying to be as conscientious as possible, within certain limitations. There are limitations in story, world, genre that we've already set up for the franchise. We can't suddenly make Nathan Drake a black protagonist, as much as it'd be super great to support something like that.

The one thing we always go back to with "Uncharted" is, it's an action-adventure genre that we're working in. It's a trope-y genre that's been set up and established previously, and it's fun. We can do our best, but ultimately what we're trying to do is create something that's just entertaining. It's not trying to send some sort of deep message.

Hopefully, no matter what race, religion, creed that somebody identifies with, we can all identify with the simplest form of storytelling, which is human dynamics and human behavior. We try to explore Nathan Drake as a human more in this game than we ever have in the previous "Uncharted" games. We try to get more personal with who Nathan Drake is.

There's a nice conflict there that you're going to play out. It gets gritty. It gets super gritty.

Naughty Dog

HuffPost called your previous game, "The Last Of Us," one of the best ever made. A lot of what made it so special was that it married gameplay with story: One didn't suffer to serve the other. Can you talk about achieving that balance?

In the simplest terms, you're trying to apply the hero's journey in the simplest way into game design. It's about the gap between expectation and result. Understanding story and how to create conflict and how to surprise the participant, the viewer, the player -- if it's movies or video games, it's all the same.

But it's not really that simple. Your games tell a story through their mechanics in a way many other games don't -- the moments of gameplay "mean" something. You don't just get the story in cutscenes.

Video games are just taking baby steps in terms of coupling really strong narrative with compelling gameplay. Naughty Dog is known for our character-driven stories, and I think that the trick that we have to pull off is that we want strong characters, and we want a strong story, which means there has to be a certain amount of sacrifice for the type of gameplay that affects the story.

So for example, we had a moment in "Uncharted 2" where you go back for [love interest] Chloe on a train. Nathan Drake is the kind of person who sticks his neck out for his friends. We choose to go on that adventure with him. You get on the train, and there's a turn, and things end up that there's a train wreck and you're stranded in the snow in the Himalayas.

We accumulate the snowstorm in the fight. As enemies approach, they surround the train wreck. You're injured. Your move-set is compromised. After you get off this high climactic point, we want to contrast it with this down moment where you collapse. You're on your own.

In this game, if you're lost, we want to open up the landscape so you have a very wide environment. We want to explore your options so you're getting back on the path. That feeling of adventure -- we're bread-crumbing you so we're not giving you the goal. Nathan Drake is lost, he's trying to assess what he should do next, and we want the player to feel the same with the controller in his hand. What do I do and where do I go?

How important is it for "Uncharted" to be accessible to people who don't play a lot of video games?

Accessibility is a huge factor. It's about simplifying down mechanics so the player can understand them, and multiplying those mechanics together to make interesting scenarios. None of the mechanics are so complex or complicated -- you don't have to read a whole guidebook on how to play through the game.

We try our best to make everything visually read. If we rely on a heads-up display to tell the player what's going on, then we feel like we're failing our jobs. We want to put the player in the experience as much as we can without being intrusive.

Finally, this is the last game in "Uncharted." You're purposefully ending a successful franchise in the era of the never-ending franchise. I imagine that must be a lot on your shoulders, to work on something that's intended as a full resolution to a franchise that a lot of people care about.

It's been brought up before that this is the first franchise that's willingly offed itself. We could probably keep selling and churn out a five, six or seven down the road.

But it's not strange to us at Naughty Dog. We decided not to do anymore Crash Bandicoot after "Crash Team Racing" rather than rehashing something where you're struggling to find a new voice or story.

Video games are the only industry where every single time someone picks up a joystick, they expect something familiar but it has to be something new. It has to have new mechanics.

James Bond has been the same basic story for 20-some-odd films. Video games don't get that luxury. You have to create something new. You have to create new mechanics. But you're still restrained by the story or the genre that you're working in. If you suddenly give Nathan Drake a jetpack, that changes who he is. You're limited.

We can try to reshape the clay, but ultimately you're still working with the same clay body. We wanted to say, what else is out there that's going to give us the passion that makes us want to pick up the joystick and come to work every day?

This interview has been edited and condensed for clarity.