I always thought about a Harry Potter RPG game similar to something like Mass Effect mixed with persona with character interactions, and with the school that appeared in the Order of Phoenix game, just better expanded.
-They should make a trilogy with years 1 and 2 - 3 and 4 - 5, 6 and 7 were your save and choices passes from game to game (the 7th year is most fastforward, and maybe not so much school, so its a much smaller segment and basically the ending.
-You attend the school after the harry potter events happen, with the kids of them (so just after the epilogue), you can befriend this characters or not (and will NOT be written like in the fucking play)
-You can choose between being a boy or a girl.
-Theres some type of new mystery, not Voldemort (not the play shit either), but shit will go down on the last game as you uncover a new villain (or join him)
-You can choose your house (with a questions minigame or just you deciding what you want to go, just like the real hat does)
-You can choose who will be your best friends at school
-Your 2 best friends will be your party
-Seasons pass like in Bully, you also attend classes were you learn new spells for your skill tree. Days pass like in persona games, with a full calendar, with morning classes, afternoon free time and night dungeons, with special events scattered around the calendar.
-The first game is much smaller, with only the castle (and diagon alley at the beggining of each year) to visit, while it starts to open more in the sequels (visiting hogsmade in the second and 3rd games).
-Theres quidditch in the the second year (so at the half of the first game), and no, you cant do like harry potter and be the chosen quidditch player of first year. You can decide not to play quidditch and do other secondary stuff instead.
-From the second game onwards you can have a girlfriend/boyfriend, and expand relationships with other characters (the first game will be more limited on that).
-Characters from the old books will still be there, Mcgonagall will be the headmistress, Hagrid will still be a teacher for animals, Harry will visit during some events as Auror, etc... Those characters are more set in stone and interactions will be not as deep as with the students. Lots of new teachers and studewnts will be created for the game.
-Collectables with the chocolate frogs card collecting (this time Harry is one of the cards obviously)
-Minigames like Exploding Snap, Wizarding Chess, friendly wizard duels are in the game, with tournaments similar to the ones on the witcher games.
-Let Rowling write the main story even if its only notes for the game writers (like the villain and stuff).
And of course the game is not canon because you can chose whatever you want.
This is how my perfect Harry potter RPG would be.
I know it would also sell a FUCKING TON, becuase fans want to experience the Hogwarts story by themselves (just look at how many millions of people Wizarding World at the different Universals attract people still, or how the london tour is always sold out as you need to get in advance always, or how merchandising still sells a fuckton). Being set after the events of the books also opens many possibilities, while still interacting with characters fans love.