What if you could build a model that solves complex Sudoku puzzles, navigates mazes, and tackles abstract reasoning — all with just 27 million parameters and 1,000 training examples? No pre-training on massive datasets, no Chain-of-Thought prompting, no language at all. That’s the claim behind the Hierarchical Reasoning Model (HRM) from Sapient Intelligence.
In this post, I’ll walk through how HRM actually works by tracing the code and architecture step by step. I’ll also cover the important follow-up critiques that question some of these claims.
