We were warned.
Then, we cooked the planet anyway.
Historical records are scattered and of volatile accuracy, but what's known is that accelerated ecological change reaped about a billion or more of the earth's population. The ensuing crisis from resource paucity led to the rise of international instability, political extremism, and terrorism on a scale unamenable by the intervention from wealthier, developed countries. A new solution was needed.
The birth of artificial intelligence didn't come from faulty software engineering or some mystical revelation of self sentience. It came when mankind deign it so. The miracle of cybernetics, nanotechnology, and neuroscience sped the natural end of human evolution. Like books, music, photography, and other media, we went digital. Immortality is simply our brains coded into binary, freeing ourselves of biological want and emancipating the shackles of ecology. Thus, the Artillect
Eternal life breeds boredom. Without survival to check our worst impulses, hedonism reigns. Cast of their physical limitations, humanity retained its... humanity. And so, while some artillects bend the environment at their whim for fun, others wage war for sport. Forgecraft, a gladitorial contest of an artillects martial skills, is born.