New unit:
1. Gravel road
2. More 2x2 size buildings: Lumber mill, Glass factory, Generator plant, Adv. obsidian brick factory, Steel mill, Advanced warehouse, drone_center
New meterial:
1. Sand
Changing:
1. Glass will made by sand
Art
1. To Modify build art: Stone quarry site, Logging plant, Obsidian quarry site, Sand mining field
Bug fixed:
1. Player click to attack fail.