The file ARK.Survival.Evolved.Lost.Island-CODEX.part15.rar suggests that it is part of a larger set of files that, when combined, will allow users to install or play the "Lost Island" expansion for the game ARK: Survival Evolved. The "CODEX" part of the filename indicates that this version of the game or expansion has been cracked or made available without a license, presumably for pirated use.

[Not specified, as it depends on the system used to view the file]

ARK.Survival.Evolved.Lost.Island-CODEX.part15.rar