It’s hard to believe, but I first played Halo twenty years ago this month. Bought the original Xbox in May 2002 (and started Game Freaks 365 a year later) refurbished from Electronics Boutique. Halo and Fusion Frenzy were my first two games. Combat Evolved is still one of my favorite Halo games along with Halo 2 and Halo: Reach.
Halo is a blast. Though I never owned myself as a kid, friends of mine did, and with Forge and Survival mode it was total chaos. Much laughs where had with Halo 3 and Reach, in the evenings where your only worry was homework and how long 'till Summer break comes. Good times 
I bought the Master Chief Collection last year. I finished Combat Evolved Anniversary Edition and started playing the classic version in Legendary Difficulty. For a game released in 2001, it looks quite good in my opinion. Looks better than some other games released in the same year, like Max Payne. CE literally evolved the FPS franchise.
Its open-ended level design and tight gameplay mechanics must’ve been a sight to behold back in 2001. This franchise is undoubtedly my favourite FPS franchise ever.
