Super Metroid is still as fun to play today as it was the day it came out. Many days have gone by through attempts to get to the end in time to get the best ending, it's a great way to make a few hours pass if you're bored. Soul Calibur on the other hand is not as fun these days as it was when it first came out. I'm voting for Metroid because I'd easily rather play it again instead of Soul Calibur 1, and it often comes up as something to do if I have about 4 hours of spare time on my hands.