so yeah this is a series which was more popular a while ago but is still making vidya
let me explain in as little stupidness as possible about this plot
You play as SORA (half of the time), a keyblade (blade that is a key WHAT CONFUSION HERE) wielder and like one of the only three or SOMETHING ???????. He is usually (unless he isnt the main character) aided by DONALD AND GOOFY which are didney characters. Also this game has didney characters. The main gameplay here is that it's an action RPG where you beat up things but it is also basically an rpg, with the main concept being that you invade didney worlds and hang out with the characters in them and break shit. as far as i know the first games plot revolves around sora's island getting fucked up, then his friend does a face heel turn and his gf disappears or something and then he is chosen (?) or something by some thing i dont know but then he gets a keyblade or maybe he had it before but anyway he becomes buds with donal and goofi and then they go and hang out in didney worlds and beat up heartless and then at the end some shit happens and his friend isnt that evil or what.
In the second game OH WAIT THE NEXT GAME CHRONOLOGICALLY IS ON THE GBA LOL. In Chain of Memories, you play a mostly bad game that is sort of like Kingdom Hearts except with cards and it's a lot more retarded as in how it plays. Sora, Donald, and Goofy go into a castle or something and meet a weird group of GOFFS called the Organization XIII. I dont know what happens because i didnt play it. In KH2, you play as roxas, who is in a paradox world that is based off the warped memories of sora or some fucking bullshit and then it turns out that he is not the main character and also sora's nobody which is some kind of weird shit i have no idea about. anyway then sora and buddiz go on a quest to find mickey mouse who is a complete badass in this game. they do some shit and then get caught up in MORE DIDNEY WORLD parties and some other shit happens and then at the end some weird shit goes down and roxas turns out to be part of the organization and one of them turns out to be the big bad forever OH FOR CHRISTS SAKE I HAVE NO IDEA
and then there were a bunch of spinoffs where you play as organization characters or something i never played them. KH3 is in the works.