Buy the game on GOG.com. GOG sells Steins;Gate Elite DRM-free. You get the exact same benefit as the CODEX crack (no internet required, copy anywhere) without the guilt or malware risk.
I can also provide a of specific Codex terms if you need help explaining the "science" in your writing.
The keyword serves as a nostalgic gateway for pirates and archivists alike. However, as the industry shifts toward consumer-friendly DRM-free platforms (GOG, itch.io), the need for cracks diminishes.