Little.nightmares.ii-codex.rar -

If you are on an older OS, you can right-click the .iso and extract its contents using WinRAR/7-Zip instead.

Navigate to your game's installation folder (where you installed it in Step 3). Little.Nightmares.II-CODEX.rar

Are you having trouble with a or a certain step in the installation process? If you are on an older OS, you can right-click the