The whole 'deep character development' thing gets thrown around a lot, but for me it's less about backstory dumps and more about characters who genuinely change because of the story's events. That's why 'Steins;Gate' still hits so hard. Okabe starts as this chuunibyou goofball doing his mad scientist bit, but the time loops and the losses grind that persona away until you see the terrified, desperate guy underneath. It's a gradual erosion, and you feel every crack.
Then there's 'The House in Fata Morgana'. It takes its sweet time, honestly—the pacing can feel glacial if you're used to fast plots. But that slowness is the point. You're peeling back layers of a curse across centuries, and each character's motivations only make sense once you've seen their full history. It's less about 'development' in a forward-moving sense and more about revelation. The characters don't so much become better people as they become fully understood, with all their flaws and tragedies laid bare.
A different approach is something like '13 Sentinels: Aegis Rim'. The character depth comes from the ensemble cast and the fragmented narrative. You get a piece of one character's perspective, then a piece of another's, and the 'development' is in how you, the player, assemble the puzzle of their relationships and hidden histories. It's interactive in a way that feels unique to the medium—the development happens in your head as much as on the screen.