I really can't say enough about these games. For starters, Super Metroid is my absolute favorite game of all time, and Prime definitely cracks the top 15. Seriously, these are both amazing games that I could come back to over and over again. If you haven't checked them out... WHAT'S WRONG WITH YOU!?!?!?
I'm just kidding. Wait until you're done reading about them to go experience perfection.