Gabe Newell speaks about it in the documentary. Here's an article about it: https://www.theverge.com/2024/11/16/24298091/gabe-newell-half-life-2-documentary-why

Gabe Newell speaks about it in the documentary. Here's an article about it: https://www.theverge.com/2024/11/16/24298091/gabe-newell-half-life-2-documentary-why-hl-3-never-happened https://www.theverge.com/2024/11/16/24298091/gabe-newell-hal... Basically, they wanted more than just simply finishing the story, they wanted to make some cool new features, similarly to what HL2 was compared to HL1.