Prime 2: Echoes is a fantastic follow-up to Prime. While still using the first-person perspective that Prime pioneered for the Metroid series, Echoes introduced several new mechanics that centred around the navigation of and combat on a planet that has the unique feature of existing in two planes of existence at once, with one world focused around light and the other darkness, sharing some features with one another and differing in others. Think like Hyrule and the Dark World in A Link to the Past. As such, the world that you explore essentially doubles.
The story once again is great, adding a bit more intrigue this time 'round. The music is fantastic in this one as well. Just like Prime 1, this game also has songs that reoccur in the Metroid games, the most notable being a version of Red Soil Wetlands in the Torvus Bog Subterranean area. Red Soil Wetlands is one of my favourite Metroid songs, of not my favourite. The final bosses of this game were a bit of a bitch to get through, but the game was still a lot of fun to play through. I even 100% it and got the Zero-Suit ending. I'm not sure if nowadays the Zero-Suit endings are still tied to how quickly you get through the game or if it's tied to completion percentage now, but one of those things did it here. Definitely worth a go.