Code Geass CYOA

From the introduction:

A world where Britain rules 1/3 of the world and controls most of the remaining world. Currently they are attacking Japan for its extremely volatile fuel source, Sakuradite. The naturally born “Brittanians” are racist to anyone who is not them and actively discriminates the “lesser” races. Also because of a mostly unified government in Europe somehow advanced mechas (called knightmares) were developed. Beings called “witches” exist which can grant someone the ability to alter themselves, or others mental state. These beings are not known to the public, and any attempt to shed light on them would likely be your downfall.