Guessed by @Veknoid_Outcast
This took a bit of a nose-dive down the list, but there's not really any particular reason for it, just a bit of shuffling around I guess. I love Metroid Fusion, it's such a unique entry in its series and has the best narrative among them too - it was the game that established the Metroid series is always gonna change with each title, and that even with all of them having very different identities, they can still tell an interesting long-running story.