Factorio

Factorio is one of the most cognitively demanding and rewarding games ever made. Stranded on an alien planet, you must build automated factories that mine, process, and launch resources into space — all while defending against increasingly aggressive alien attacks. The game scales from the simplicity of a single belt and furnace to an overwhelming web of production lines, circuits, and defensive perimeters. Its achievement of a perfectly balanced difficulty curve across hundreds of hours is almost miraculous. Few games inspire the same level of compulsive engagement.