Dorago, that plot oozed originality. I swear.
I greatly disliked the first episodes only when I'm looking back and seeing all the incredibly stupid moves they made in the past. A clear example was from Kai himself in the game against Kamui. He called Baryi to boost Nehelam, got a Heal with the attacking Aleph, who Kamui didn't even guard against, and put the +5000 on Aleph instead of the standing Nehalem..
tbh, in the starting episodes, the best player was what, Kamui? Kourin? Kourin is a terrible player.
Also, as far as I know, the Manga is lost to us.
And if you need places to watch it, use gogoanime or Crunchyroll.