I just finished Hollow Knight this week (basic ending, didn't go out of my way to find items I didn't organically come across). Metroidvanias and 2d side-scrollers in general haven't traditionally been my thing, but I was persuaded by Monty Zander's video and...yeah, it's as good as everyone says. The world is surprisingly immersive for its format and the gameplay is tight and rewarding. Abilities and enemy variety were always changing the way I played, and the different areas each had their own identities and obstacles. The sense of excitement on unlocking a new area and getting to explore it was on par with Elden Ring.
Unfortunately, I moved on to Kena Bridge of Spirits, which I think is a pretty good game so far, but it has some AA jank that I think stands out more after the fine tuning in Hollow Knight, and the combat is a lot more rote. Trying not to be too harsh though because not everything can be what Hollow Knight is, obviously.