Mecha pilots could challenge again and again, and try as many times as they liked.
Regardless of whether they cleared it or not, everything in the Age-Old Shadow would be reset, including the memories of monsters and bosses.
Each challenge was equivalent to a brand new world.
That's why mecha pilots used the term "abyss carbon copy" to describe the world of the Age-Old Shadow.
After all, it was so similar to game copies.
If it weren't for the fact that one could truly die, it would be purely a virtual reality game, a training illusion.
The bosses of Abyss difficulty level, however, broke this rule.
They remembered every challenger, every experience of being challenged.
This meant that it, or they, might not be just false illusions.
They might be truly existing beings!
"No wonder the Symbol of the Alliance said this is the true abyss..."
"At lower difficulty levels, we're challenging the Age-Old Shadow constructed by the abyss."