GTA 6 puts two playable characters at its centre, Jason Duval and Lucia Caminos, and treats them as a pair rather than as alternating solo runs. That is easy to describe and hard to build.
The state problem
A single-protagonist open world only has to track one set of relationships, one inventory, one reputation, one position. Two characters double all of it and then add the connections between them: what one knows that the other does not, where each was when something happened, how a choice made by one constrains the other.
Most games that offer multiple characters solve this by keeping them separate. Different chapters, different areas, minimal overlap. Genuinely interleaving them is a much larger problem.
The pacing problem
Switching characters resets the player’s sense of momentum. Done well, it works like a cut in film: a scene ends at the right moment and the next one starts somewhere more interesting. Done badly, it feels like being pulled out of something you were enjoying.
The difference is almost entirely about who controls the timing. A switch the player chooses feels like agency. A switch the game imposes feels like an interruption, unless the writing has earned it.
Why the writing carries more weight
With one protagonist, the player fills in the character. With two, the game has to establish a relationship – and relationships need dialogue, shared history, and disagreement. That is more writing, more performance capture, and more places where a wrong note is noticeable.
What to look for
The tell is whether the two characters feel like different people to play, not just different models. Different pacing, different capabilities, different reactions from the world. If switching changes only the face in the corner of the screen, the structure is decoration.
Why it is worth attempting
Because the alternative is a protagonist who is a container rather than a person. Open-world games have leaned on the silent or near-silent lead for years precisely because a strongly characterised one conflicts with player freedom. Putting two characters in relationship is one of the few structures that lets a game have both a real voice and a real sandbox.