Basically:
Sora
1.Sora loses all his memories of Kairi,replacing them with fake ones.
2.He works his way to the top of Oblivion to regain them.
3.He kills a few Organization members.
4. After reaching the top, a witch (Namine) agrees to give back all of his memories.
5. He is sealed inside an egg, set to hatch in a year.
Riku
1.Awakes in an endless abyss
2.He receives cards and is warped to Hollow Bastion.
3.He fights Vexan, but Vexan takes his DNA during the fight.
4.He continues towards the top of Oblivion, hoping to find Mickey.
5.He slaughteres the remaining organization members in Oblivion.
6.He finds Mickey.
7.He abandons the Darkness, and joins the Light side.
8.He defeats his remaining memories of Ansem.
There ya go!
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)