Gavhack is a modded Minecraft client on the game version 1.7.2 built using ModCoderPack to decompile minecraft.
Optifine and the World Downloder mod have been added to the source code, and the mod itself is written in Kotlin.
There are also some minor fixes added, such as making player skins and capes work properly again.
This version of Gavhack is built on Minecraft version 1.7.2 for the server Alfheim.pw, and is primarily designed to be played on that server.