Gmod-sdk-x64_[cheate....com]_

It looks like you're referring to an x64 version of the Gaztoof GMod-SDK , a software development kit often used for creating or updating cheats for Garry's Mod.

: Provides the necessary interfaces to interact with the Garry's Mod engine (based on the Source engine). GMod-SDK-x64_[cheate....com]_

: Use a compiler like Visual Studio to build the source code from the GitHub repository into a 64-bit DLL. It looks like you're referring to an x64