Kirigaya Kazuto, no, Kirito, could do little more than sigh softly and smile. He turned round and round, looking at all the brand new SAO players, yet not looking at anyone at all. He was, as a beta player, not surprised by how beautiful the first town was, nor was he planning to stay there even a little bit longer. Because, as a beta player, Kirito knew what others didn't. He knew the good hunting spots, the best quests, and above all, how to clear a floor. Kirito wasn't the only one. 1 to 10 of all the players were former beta players. 10 per cent had a great advantage over the rest. In this survival game.
Kirito took one last look around him before he started walking, and thereby his long and lonely journey -he was a solo player after all-. And that's when it got weird. He would've sworn someone called him, no- someone should have. What was that feeling?
Kirito never met Klein. He never went to a floor clear convention because no convention was ever held- Diable had died on the very first day.
Kirito never met Asuna.
Asuna never met Kirito. No one told her she would be strong. She never got far.
Kirito cleared floor after floor, but soloing bosses was rather hard and it was a miracle he hadn't died yet. A miracle? A curse! No matter what he did, somehow he'd survive. He became the black mage, for his fighting style had something magical, something strange that made him never lose a battle. Kirito wondered what it was. He wondered what it could be, and why it was there.
After Kirito beat the last floor master, the game was over. It wasn't cleared though; it had been completed. Kirito became king of the castle, and when, years later, others came to clear the last boss, they faced him. Kirito. The black mage. The one who had been a myth, a story to keep the others going. How he had unintentionally, unknowingly given them hope, so had he crushed them, defeated them.
The game never got cleared, because that was the bug. All games have bugs, glitches, loopholes.
The game never got cleared. And of this survival game, no survivors were left.