The Nioh Complete Edition is a bundle that includes the base game, all three DLCs (Blood of the Nioh, The Dragonfly's Vanguard, and Darkness in the Capital), and additional content. This edition was released on November 7, 2017, for PlayStation 4 and on February 1, 2018, for Microsoft Windows.
The CODEX release refers to a cracked version of the game, which was leaked and made available on the internet. CODEX is a notorious group known for cracking and releasing pirated copies of games.
Nioh is an action-adventure game developed by Team Ninja and published by Koei Tecmo. The game was initially released in 2017 for the PlayStation 4 and later for Microsoft Windows in 2018.