Galaxy Survivor 3D: Back Home is an Android strategy game centered on survival. You control a character who builds, collects resources and defends against invaders threatening the last tree on Earth. The core activity is managing materials and structures while planning how to hold off attacks.
Gathering resources and building factories
The character can collect resources and combine them to build factories. The listing says this supports exploring the universe, and that opening new worlds and paths is part of the progression. Exploring each area and looking for resources is presented as necessary to succeed.
Weapons, fences and ammunition
Gathered materials can be used to build defensive weapons and fences, and to produce ammo. Defense is the central challenge: you choose defense strategies to fight invaders and protect the last tree on Earth.
Controls and planning
The listing describes the controls as simple and easy to use for building, collecting and defending. Because the game is built around devising a defense strategy to outwit enemies, planning how to defend is a central part of play.