The original Xbox such a power house of a console back when it launched and Halo : Combat Evolved was a great game to showcase that power.

Halo: CE is probably one of the most significant games to me personally.  I have fond memories of doing two 12+ hour marathon sessions of co-op with my brother over thanksgiving weekend 2001.  

One night, we both fell asleep in gaming position, in front of the TV.  Another time, I remember having to work for several minutes to get my hands out of controller grip shape when I went to the restroom, after several hours without any break at all.  

This may sound cheesy - this is one of the coolest memories of my life, gaming or otherwise.  Consequently, the sentimentality factor with Halo is huge for me.    

Nothing like a great gaming session with friends and family.

Just wondering have to watched Halo Legends?  It's the annimae based on Halo.

The most significant console FPS besides GoldenEye, can't believe it's been 15 years! Imagine what would have happened to the Xbox brand WITHOUT Halo...

I Bought my Xbox and Halo:CE along with DoA3 and Munch day 1. Pulled up to K-mart an hour before opening. Me and 3 other strangers. Couple hours later, my friend and I were co-oping through the snow in a scorpion tank.

Coming off of Quake III Arena for Dreamcast, a game with one analog stick, we had to play in south paw!

First mission: Looking at the grass for half an hour.

Halo is by far the best gaming franchise ever (of course IMO)
The depth of the story, the pure gameplay, the competitive multiplayer, from 1on1 up to 16vs16, it all just works out. I don't think any FPS offers such a variety.

It has been 15 great years, especially the 360 era. And I love Halo even more today than ever before, wouldn´t have been an XBox fan without it really :).

No, I have not.  I've actually never read or watched any Halo stuff outside of the games.  I've often thought that I should do so though.

Which games are they?