Apocalypse: Empire Technology Tree

The world after the disaster is devastated, and the outbreak of nuclear war has made most of the land unviable. Plant mutations, unknown civilization, and human beings' technology continues to upgrade in order to resist the tide of beasts, but they are still unable to compete with the powerful alien beasts. The earth is in an unprecedented crisis, and it is also generally united to re-divide the world based on regional defense. The original concept of a country has become seven different war zones. A few years after the alien beasts stopped attacking for some reason, scientists from various countries gathered all their scientific research results on a special chip, and the N3 ultimate intelligence brain was born, codenamed Nirvana. N3's learning and evolutionary capabilities exceeded scientists' expectations. Humanity's first combat-type heavy mecha was successfully developed and put into use a few years after the birth of N3. … In an explosion, the N3's ultimate brain disappeared. Fortunately, in the years since N3 was owned, the earth's technological level has grown explosively, and it has the ability to manufacture combat-type mechas and has the ability to compete with alien beasts.