Attack on Titan is protected under international copyright law (Koei Tecmo, Kodansha). Downloading a “corepack free” version is software piracy. While individual users are rarely sued, your ISP may throttle your connection or send cease-and-desist letters. In countries like Germany or Japan, fines for torrenting anime games are common.
"CorePack" refers to a specific type of game repacker, similar to FitGirl or DODI. These groups are known for creating highly compressed versions of PC games. attack on titan wings of freedom corepack free