Let's get this out of the way first, Prime is not a first-person shooter. It is a first-person adventure. That doesn't matter all that you need to call it is perfection. It is like Retro Studios has taken the amazing Super Metroid and turned it into 3D.
This could definitely be an answer to Halo, in fact I prefer it over Halo's single player campaign (just barely). Every thing that you could love about Metroid is here. The only problem with this game is the little scavenger hunt at the end, but it's no biggie. Any person who might be skeptical of the first-person point-of-view should not worry. Nintendo and Retro have created one of the premier games of all-time, and the best game on the Gamecube.