Capturing the narrative experience the player feels through gameplay without said gameplay present. Obviously there's no one-size fits all answer, but I think this can apply to a lot of them. Faithfulness alone isn't always enough.

As case studies, Danganronpa the Animation and the respective Persona 4 and 5 anime very faithfully recreate the plot of their games, but utterly fail to realise the experience of them. I remember watching DGR before playing the game and finding something really...off about how the cast investigate the various murders. There's just these extended, inert sequences of the characters spotting clues with no commentary on them, and then during the class trial Naegi just effortlessly strings all the clues together. There's a reason this rings so hollow- this is not how it feels to solve the mystery in Danganronpa games. As you're collecting each clue, you'll start speculating as to how they're relevent, and this deductive process continues throughout the trial. Compare this to any other detective story- there is always a strong sense of logical continuity. Detective Conan solves this problem by giving Conan a consistent interior monologue throughout the investigation of each case. If you're not involved in the deductive process, it just feels like watching a strategy guide.

Persona 5 the Animation bothered me for a different reason. I watched up to the end of Kamoshida's palace. For one, Amamiya is presented as a silent self-insert, rather than trying to embellish his personality based on Joker's more sassy dialogue options. The other is how...pointless the palaces feel. The dungeon-crawling experience is the challenge the Phantom Thieves take on. The arduous struggle of making your way through a complex labyrinth of enemies. And here they just get in and rush straight to the end to take on the boss, any exploration is skipped over. The plot of the game is stripped down to its cliffnotes and set-pieces, and as a result, nothing feels like it matters. Truth be told, I'm not sure an ideal anime adaptation of this could exist as things stand. The anime industry is moving to increasingly short-form productions and my blue sky pitch for a Persona adaptation would be a 50+ episode affair. For the palaces, particularly the early ones, I'd spent several episodes on the thieves getting to grips with the unique challenges each ones pose and the tougher fights they'd find with in. This isn't even getting into how you lace in the Confidants which...honestly, I'm not sure even translates mediums. idk how you present those in anime form without completely killing the pace dead in repetitive, intrusive ways. Anyway, I've gotten quite thoroughly away from the question at this point but I'll take any excuse to ramble, thanks.