Since he was the "Morganna" Of G.U., and basically, as I see it, was continuing her legacy indirectly (ie, how Hoffman is continuing Jigsaw's work in the later Saw movies) as "Tri-Edge", does it not strike you as odd that he was not the final boss? In other forms of G.U., he is essentially that...now, Cubia makes a great final boss but what they've could done is this:
After taking a gamble on using the Rebirth, Ovan makes a horrifying discovery:As Tri-Edge has grown in power and intelligence over the last few months while resting in his arm, he has "learned" and modified the Rebirth program...so after pushing Ovan to the point where he is forced to manipulate Haseo into activating it, Ovan unleashes an even greater monster...the anti-existence within himself, the monster we all deny that is there within us...his version of Cubia now under the control of Tri-Edge.
Now, the AIDA grow at an alarming rate...all players in "The World" instantly find themselves trapped in the game world again unable to run. Multiple ANNAs and Helen run rampant across thousands of fields. The Epitaph Users cannot possibly stop them all...until Tartarga comes in for the save. Ovan, now essentially a prison in his own body, is taken almost completely over by Tri-Edge who tries to establish complete control. Ovan, still resisting, tries to assert control but is quickly losing control...Aina is saved somehow and brought aboard Tartarga before the Creator's Room is destroyed.
Haseo and the others, unsure of what to do now, propose one last strategy...strike now while the newly developed Cubia is still vulnerable to attack and hasn't developed complete control over the system. Zelkova, leet hacker that he is, locates Cubia's central locale and directs Tartarga to the exact field...but before they go, Zelkova proposes that he look over Haseo's PC...giving him a "special book". Taking hold, Zelkova instructs each of the Epitaph Users to place their hand on the book, and one by one, each of them merges with Haseo, along with Ovan's obtained Epitaph, becoming the X=th form...but not before a "test" from his Epitaph to see if he is ready to become the Key of Twilight...
A conversation between Haseo and Skeith takes place...similar to the one from before in the game, but a little longer and more revealing. If you can put some input on this AT, it would be most welcome...anyway, long story short, Haseo gets X-Form and confronts Cubia along with Sirius and Sophora, his two AI beast guardians (in my mind

Epic battles ensue, and before you know it...we're inside Cubia, and it's Haseo versus Ovan. After a fleeting battle between them all, Ovan grins...his glasses glowing orange as his data starts to fizzle.
"Y-You really have grown stronger Haseo...strong enough."
"Strong enough? To what, stomp on you? You've done so much damage to so many people that it makes me sick inside...sick that I actually looked up to you the way I did. And yet...yet I still want to look up to you, Ovan. Some...part of me actually almost appreciates what you did."
"That...would be the void in your heart, Haseo. The darkness that we all deny that's there."
"Then allow me to fill yours."Haseo points his guns up.
The screen fades to black as we hear two guns fire off...
Yeah, the ending could be better...XD
Do you think Ovan deserved to be the final boss?