Alfonso John Romero is born in Colorado Springs, Colorado. His early exposure to computers and technology begins to shape his future path.

Romero's interest in computers is sparked early in his life. He begins experimenting with various systems and learning basic programming concepts. Details on specific machines or languages are limited, but this is a crucial period for cultivating his passion.

Romero starts creating his first video games on Apple II computers, marking the beginning of his journey into game development. These early projects were rudimentary but critical in honing his skills.

Romero dedicates himself to learning assembly language, a crucial skill for game development in the era of limited hardware resources. This knowledge would later prove essential for his work at id Software.

Before id Software, Romero starts developing and selling his games commercially, though details are scarce. This phase allowed him to gain real-world experience and further refine his programming skills.