Noah is a filler character anyway
Also we have the ace of o'brien, amon and jim since like 2 years ago, and theres nothing that say they will be unlocked one day.
Gozaburo Kaiba would actually be pretty cool in the game. I can image the lines between him, Seto, and Mokuba. 5Ds I want Sherry and most of the dark Signers to be in.
In video games, the main card of his deck's typically Gaia Plate or Multiple Piece Golem (being a Rock-Type fusion, it's pretty fitting.)
He didn't really have an ace in the anime. His Fossil Fusions took advantage of his opponents' cards, he didn't really favour one. (He did use Skullgios against the Duel Ghouls, so I guess maybe you could consider that his "main" one, but I wouldn't personally.