GregTech 5 Unofficial is a GregoriusT-approved port of GregTech 5, updated for later versions of Minecraft Forge, and fixes several long-standing issues and bugs. There are two development branches; 5.08.xx is focused mainly on fixes and additions to machines, while 5.09.xx focuses on fixes a little deeper in the code, and also includes several balance changes to recipes and bugfixes to the API.