WHAT SHOULD GO IN A CHARACTER FOCUSED GAME

I think the most important thing is to get players actually like the characters and feel connected to them.

Then you kill off the most liked character.

And then everybody will talk about your game.

Vignettes couldn't hurt. Have you ever played any of Namco's "Tales of..." games? They have optional skits between the characters that flesh out their personalities. It's arguably one of the strongest trademarks of the series.

I suppose that's a bit of a passive way to go, though. You could expand them into side-quests, or weave them into the main plot.

Another good thing to do is MAKE A MIND MAP (I hate the way that sounds, it reminds me of grade school). Write some very basic characteristics such as "hates swimming" or "plays the trumpet", then expand on those ideas.

Yeah, agreed. I didn't mean that type of vignette-triggering system, but some way of including short character-fleshing flavour stories.

Not so much bad, it's just that everybody's so condescending when you're a child.

I think Xenoblade Chronicles is a good example of character-driven stories. Sure, then characters themselves are super generic initially, but I loved the way they all react to each other during battle, as well as the Heart-to-Heart system.

A tried and true method of developing characters (For me, at least), is having them get angry at each other. The whole, "Group of friends going to save the world," trope is really boring for me, so I make characters with vastly different opinions, values, and beliefs. So when one character does something that violates another character's beliefs, the other character will get angry and argue. Through arguments, characters have their chances to stand up for their beliefs, and explain their reasoning why they believe such. This allows the players to really get to know them and understand them, even if they don't agree with them. I think a well developed character that I hate is much more satisfying to get to know than a poorly developed character with one or two good qualities.

One thing to avoid at all costs is the One Trick Pony character. That is a character who's entire likability is centered around one trait that overshadows all else. An example would be the Airhead character. Sure, the character could be fighting for the entire world's future, but if this person's sole identifying trait is being a klutz, then the character's depth is thinner than a piece of paper. A good example of this is Kaguya from Super Robot Taisen OG: Endless Frontier. Her sole character trait is she's a shy girl who wore a skimpy outfit. SNORE!

Kaguya actually is a good segue into another point. Something else to avoid is a massive disconnect between story and gameplay when it comes to a characters personality. If a character is super shy and timid, they SHOULD NOT be able to unleash super powerful, flashy abilities immediately in combat. Likewise, if a character is outgoing, strong willed, and brave, they should have skills and stats that reflect that. As the story goes on, those changes can be made. However, it's very hard to believe that a character that is too shy to talk to someone is capable of saying badass quotes in battle while throwing a bunch of group obliterating fireballs.

You're making a game, not writing a book. Use the medium you have to your advantage. Part of playing an RPG is being able to lead a group of characters through the story and watching how characters develop physically, mentally, psychologically, and emotionally. The best way to do that is knowing the character's individual strengths and weaknesses. That is also a great way to get to know characters.

Character-focussed games focus on the characters and how they fight against whatever they need to. There's an external world issue but the issues within the group help to drive the story along. Usually the characters go on the Hero's Journey - except an internal one as well as the external. That is, they each go on a personalised version of the journey that helps them grow as people while also engaging in the larger Hero's Journey to save the world.

If your characters are exactly the same as they were when they began the journey, then there's an issue. Changes can be subtle or large but there should be something there that shows that they've progressed from the person they were at the start of the story in some way.
It may be as simple as a country lad who was torn between the city life and the country life finally realising that what he wanted wasn't adventure in the city, but to feel connected to something, and finally leaving his hometown and returning he has come to cherish the peace of the place.
It could also be a once-drunken piratess who was in mourning over her lost family finally coming to terms with them never returning and deciding to get back up and live life to the fullest.
Even a shy priestess who grew to understand her own strength and finally claim her right as the leader of the religious order in which she served, now that her bonds have deepened with the Goddess of said religion.

The journey to those changes being explored is how you show character focus - the story of their journey is tied to those self-discoveries and what moves the story along. External stories can interject - an evil Overlord who sought to steal the Priestess brings her to meet the naive country lad in the first place - the but main story is about the group, how they meet, how they grow and how they do what the story asks them to do.