I don't know what it is but everything about this game just does it for me. Incredibly smooth, fluid, and satisfying gameplay. This game is at its best when you're just running through everything, killing enemies with pinpoint precision and doing all these cool things. Except actually, this game is at its best during the boss fights. The final boss is probably my favorite ever in a video game. It's incredibly challenging with tons of crazy mechanics and an amazing theme and narratively, a really cool way to cap off the end of this arc for the series. The soundtrack isn't something you'd really want to listen to on its own, but it sets the tone super well and adds to the atmosphere. Speaking of, it should be a given for Metroid but the atmosphere is incredible. The visuals are insanely impressive on this game with these gorgeous backgrounds that seem to go on forever and these insanely detailed environments. Some of them feel kinda samey but then they mix things up when the area gets frozen over or you enter Donkey Kong's Jungle. I could probably play this game over and over and never get tired of how fun it is. Genuinely one of the best gaming experiences of my life and I'm so glad that this game not only came out, but that more 2D Metroid is probably coming on the horizon. And after this? I can't wait to see what comes next for this series. 10/10.