Sorry.
Forgot all about them.
Fixing...
EDIT: Fixed.

I meant the whole KH story.

Do you mean like what happened in the games before KH:3D?
If that's the case, I can explain it perfectly.
If no, then I don't know.

Yes.

Sora and Riku start out in KH1 on Destiny Islands. They try to build a raft to go to different worlds. However, things don't go as planned. Riku gets sucked into the darkness. Sora starts his journey searching for him with Donald and Goofy.
In Chain of Memories, Sora tries to find Riku in a castle called Castle Oblivion. However, the Organization try to get Sora to come to the Organization to overthrow their leader.
In KH2, Sora tries to find Riku and King Mickey in different worlds, but Organization XIII try to stop him from doing so.
In Birth by Sleep, Terra, Aqua, and Ventus are trying to become Keyblade Masters. This has happened 10 years ago, which means Sora was 4 and Riku was 5 years old. This game starts the whole KH storyline.
The side games don't truly affect the story in any way.
^Read this. Did this help you?

Probably not, too brief.

The KH storyline is stupid, and incredibly overcomplicated. I wouldn't expect someone to be able to summarize it well, man.

Regarding the trailer: I thought I was done with KH after the idiotic story changes and awful level curve in BBS, but I'll admit, that looks f*** awesome.

I only explained the beginning of the just because it's too much to say the rest of the story.
Man, the storylines are really long.

It helped a little,guess I will be scanning wikis.

I played every kh, but the story is still sketchy to me, but ill try to help....correct me if im wrong. im typing this hoping you have some idea about each game...

in kh1 sora and riku live on destiny islands together, always dreaming of going to other worlds, and wondering what was beyong their small island. One day kairi washes up on their island, she becomes part of their group. the three of them have a secret spot in this cave like crawl space area on the island, theres a mysterious door in there that they seem to never have questioned for some reason. A couple years later they decide to build a raft to leave their island and visit other worlds. the night before they take off theres a storm, so sora goes outside to check on the raft, heartless appear every where and he doesn't know whats going on. riku leaves the islands through some dark portal, sora tried to go with him but couldnt, sora finds kairi in their secret spot, the weird door flys open and they get sucked in. meanwhile in disney castle, mickey the king has gone missing, he left a note saying that stars were blinking out (meaning worlds were disapearnig) so he went to investigate it. He told Donald to go with goofy and find the key bearer. The two of them run into sora in traverse town and they team up. Soras goal is to find riku and kairi. They travel through lots of different worlds looking for them.... mean while riku is tricked by maleficent, she tells him that sora has moved on and got new friends (donal and goofy) also she tells him that she can help him save kairi, so riku sort of turns bad for a little bit. maleficents plan was to gather the 7 princesses of heart to open the door to kingdom hearts. she also ontrols the heartless and shes the one whos been sending them to the different worlds, to capture the princesses.. some way throgh the game you find out that kairi is one of the 7 princesses. **this is important** at one point towards the end, sora is turned into a heartless, but kairi recognizes the heartless is him, hugs it, and he turns back. this is an important fact for KH 2. towards the end of the game u fight maleficent, who up until now was the main antagonist. after you beat her u fight riku (who at this point isnt really riku, he is being posessed by this guy ansem. Ansem is the seeker of darkness, and he studied the ehartless. one day he vanished, and his studies (called the ansem reports) are scattered, u collect them through out the game. He possessed riku to gain a physical appearence or something...i think thats what happened lol. so at the end u fight ansem in a cool, pretty long fight. Ansem opens the door to kingdom hearts, which he thinks will be dark power so he can defeat sora, but it turns out to be light to his surprise, and hes defeated, giving riku his body back. At the end theres a huge door and behind it is an infinite number of heartless, sora donald and goofy struggle trying to close it, riku turns out to be behind the door and helps them close it, from the other side with all the heartless. (bamf) mickey is behind the door with riku as well (his first appearence in the game) and he helps to. (Riku and mickey are tight)....

kairi is safe at destiny islands, sora tells her hell come back to her after he saves riku and mickey. At the end of the game mickeys dog pluto gives them a letter from mickey- leading to the next game, chain of memories.

i forget what the letter said tbh....oh well.
they wind up in this place called castle oblivion. This is where organization XIII makes their appearence. sora and co are told that the farther they dwelve into castle oblivion, they will lose more and more memories. Riku also ends up in Castle Oblivion because his heart connects with Sora's, who is also in the castle. What remains of ansem tries to take over riku again, but he can't, but he gives riku dark powers. riku is scared of the darkness, more than anyone. but mickey helps riku, which is why they are so close. This guy Diz who is the leader of orginazation XIII gives riku a card that will give ansem a physical form, so that riku can defeat ansem and get rid of him for good. he defeats him, but he can feel theres still darkness in his heart. At the end of rikus story he sets off with mickey to get rid of ansem once and for all. back to sora, he meets this girl namine who is a witch that can rearrange pplz memories. she does this to sora and makes him forget about kairi, on orders by org.13. At the end of the game after sora defeats most of the members of organization xiii, namine tells sora donald and goofy to sleep in these memory pods, which would slowly restore their memory.

Next, KH 358/2 days

When sora turned into a heartless in KH1, he created a nobody, Roxas. (namine is also a nobody, she is kairis nobody)
Roxas is discovered by organization xiii and brought to their hideout or w.e, and they recruit him. he starts off not knowing anything about anything, and slowly learns, they put him on missions with 2 friends, axel and xion. Xion later turns out to be a replica of roxas, created from soras leaked memories. The organization planned on making xion absorb roxas, to create a new sora, or something stupid like that. But anyway the act of xion simply living, completely halted soras memory restoration. When xion finds out the truth, she wants to return soras memories to him, but can't. at the end of the game roxas and xion meet on top of their usual spot, the clock tower, xion removes her hood and her face is soras, since his memories are flowing into her so much at this point, they fight and roxas wins. Xion asks roxas to not let xemnas control kingdom hearts. Xemnas is the nobody counterpart of ansem...ansem was the heartless version of this guy xehanort... ugh so confusing... but xemnas is one of the main antagonists, hes the leader of org. 13, and the main bad guy in kh 2. Anyway so riku hunts down roxas, and they both fight, riku wins and brings roxas to Diz.

KH2

You start off as roxas, a new roxas basically, diz erased his memories of organization xiii who thinks hes a normal kid leading a normal life with his friends. Roxas realizes strange things going on, and he always has dreams about sora, he investigates. he finds diz and finds out the truth, that his life is a lie, all his friends and even the town he lived in were just creations made by Diz. after like 7 f*** hours of gameplay, roxas finds the room where sora donald and goofy are sleeping in their restoration pods, the pods open up after all the time, roxas disapears, its kinda sad. sora is older now, i think it takes place a year later. They can not remember anything about castle oblivion, and they continue their journey to find mickey and riku.


--- im all typed up for now...haha feel free to not read this, kinda went off their....

Mostly right, nothing major to touch on. Continuing from where [NU] left off:

Once Sora and co. wake up they are lead through Twilight Town, where KH2 had all taken place so far, and end up in a giant tower where Yen Sid resigns. He explains about how the world's have been connected differently and the nobodies as well as the Organization. At which time they continue travelling worlds and derping around, meeting Org. members periodically. Well at one point a giant f*** war breaks out in Hollow Bastion and everyone is against everyone. The Final Fantasy characters, Maleficent (who ends up being still alive) and the Org. Eventually this war makes it's way, albeit indirectly, to the Org. stronghold. Axel kills himself to get rid of a huge army of nobodies in a dark corridor and opens the way there, and once inside they find out that Riku has morphed back into Ansem and they meet the real Ansem, who they found out was NOT the Seeker of Darkness back in Hollow Bastion, and continue to beat down on org. members. Well Ansem tries to absorb the moon, which is an artificial KH, and in such blows himself up and changes Riku back to normal. You make your way back up, beat the ever living s*** out of Xemnas, and now Sora and Riku are back at Destiny Islands.

Then in Coded Jiminy finds a very strange passage in his journals and digitalizes it to find out the meaning. Turns out it's bugged to all hell and it has to be decoded. I, personally, haven't played coded so if someone can tell me what happens there it'd be nice.

oops I lied, never played coded either.

In Re:Coded, Mickey creates a Data-Sora and sends him to the worlds in the journal, trying to debug them.
Eventually, Pete and Maleficent break Sora's Keyblade.
Donald and Goofy go inside the journal, helping Sora along the way.
Before Sora fights Pete and Data-Riku, Sora gets his Keyblade back and defeats Pete and Data-Riku.
Finally, Sora finds out the true cause of the bugs in the journal.
Sora's Heartless is causing the bugs to appear.
In the end, Sora's Heartless dies and Mickey, Donald, and Goofy go back to Disney Castle, leading up to the end of KH2, when Sora gets the letter from Mickey.
I hope this helped...

There's also BBS ~Vol.2~

Which shows Aqua fighting through the realm of Darkness, apparently.

Thanks guys,the only KH game I played before is 385/2(understood most of it) and knew a little about KH1,but it's way more complicated than I thought it would be.One thingout of many others I don't get is why the organization is considered bad,they are just trying to be somebody with a heart again,right?