My list was in no particular order, there are some other games that didnt make the list but I tried to pick games that had a profound effect on my life.
Gears of war 2 was not my first gears “technically” but that game is what started my love for the franchise in the first place. Playing split screen with my childhood friend while killing locust is just something I cherish very much.
Halo 2 was my first introduction into shooter games, I dont have much to say about 2 because It was a brief time when I played it. But it deserves a spot on my list because it’s what started it all.
Halo 3 ODST is personally my favorite halo story, i love everything about the game. I have a great memory of my mom coming home late after work and pulling out a copy of the game from her purse, I popped it in immediately and got to work 
Destroy all Humans! Is such a fun game for me, its mindless, Pox is literally voiced by the person who voiced Zim in Invader Zim, Cryptos a great main character(s), and I just love the setting, good old 1950s America where they blame Communist Russia for just about anything Crypto does
. that game was a staple back when I used to play on my uncles PS2.
Dying Light was one of those games that I would stay up all night playing, I love zombie games and movies, and for me Dying Light just gave me what I liked, some of the characters are pretty forgettable but the action and environment is so good imo.
Fallout 4 was a Christmas gift for me, I had never played a fallout game prior to that so I didnt really know what I was expecting lol. However, after playing I just fell in love with the franchise, its definitely my favorite open world series, I get so invested in the world around the Sole Survivor/Courier/Lone Wanderer. I one day hope to get the chance to play fallout 1 and 2 as I’ve heard incredible things about them.
Grand Theft Auto 5 (Online) introduced me to people who are going to be lifelong friends, I had a rough year at school and gta online was how I spent my free time, I would drive around LS picking people up so we could do things, I managed to run into some nice guy who wanted to tag along with me, he invited me to his party where he introduced me to his other friend. We’ve been friends for 5+ years now and we are all really close.
Batman Arkham City is one another game I spent plenty of nights staying up on lol. However, I didnt own it, my friend did. So I would go sleepover at his house and that was what we usually played, I’m not even a batman fan either but I just really think those games are some of the best superhero videogames to ever exist. One thing that Arkham City doesnt have is Arkham Asylum Harley Quinn. Ifykyk 
Call of Duty was introduced to me by my dad who gave me a copy of MW2, me and him were already playing cod together because of MW2 but Black Ops was something special. We spent plenty of hours grinding out Domination (I was a TDM only player at that time but we usually ran that or ground war lol). Its my favorite cod hands down. The maps, the weapons, the era, the zombies, all timeless. The black ops series in general is superior to the MW series, (someone had to say it and I’m gonna be the one to say it
).
So those are my reasons for my games.