The 1.5 branch moved the game to Unity 2020.2.2f1, which provided better support for modern hardware and fixed long-standing physics bugs.
This specific .rar file is a "crack" or "repack" provided by the group CODEX, allowing the game to run without standard DRM (Digital Rights Management) like Steam or GOG. Safety and Content Warning Hollow.Knight.Update.v1.5.78.11833-CODEX.rar
Files from third-party "scene" sources often carry risks of malware or unwanted scripts. It is always recommended to verify such files through tools like VirusTotal . Hollow.Knight.Update.v1.5.78.11833-CODEX.rar