Celeste

Wait — a precision platformer with thousands of deaths on a "cozy" list? Yes, because Celeste's Assist Mode lets you slow the game down, add dashes, or become invincible, and the developers explicitly state: "Celeste was designed to be a challenging game, but we want everyone to be able to experience it. There is no shame in using Assist Mode." The story of Madeline climbing a mountain while battling anxiety and depression resonated so deeply that it became a touchstone for gaming's mental health conversation. Also: the B-sides are brutally hard if you want that. 1.5 million copies sold.