Collection of ML Deep Dives on complex research

During an internet rabbit hole I ran across an awesome site that collected some complex research papers, like AlphaGo and linked all the other papers that explained the complexity. Like ML the hard way. I can’t recall if I found it through Medium, Jane Street Tech Blog, GitHub or by serendipity! But I do know I completely failed to bookmark it and can’t find it again. Hoping, out of desperation, this resonates with someone who knows this magical site and can share! TIA