Great idea for a thread, this brings back so many memories. Lemme see...
Ordered by when I first came into contact with a particular system. The first few ones I am not really sure, I was still a wee toddler, my memory got fuzzy.
PS1: Megaman X6. God I love this game, along with X4, X5, and X8, they seem to get a lot of flak though
Gameboy Color: Super Mario. I have no idea what this one is really, I presume the colored Super Mario Bros is the first Mario, but this wasn't the one I played. The first Mario I played was one with no color, but with the same mechanics, I vaguely recall there being a level with chinese zombies jumping at you that wouldn't stay dead towards the end, then the final level was played in an airship, would appreciate if anyone more knowledgeable could clarify.
Gameboy Advance: A japanese Yu Gi Oh title. I don't understand Japanese, so I used my knowledge of Chinese and game mechanics + card effects from the real game to YOLO my way to the end, involved a shit tonne of walking around talking to everyone and battling everyone multiple times to trigger the next scene though, I laugh at the dedication I used to have as a gamer, 10 year old me would laugh at current me so hard.
PS2: Rockman X7. Yes another Japanese title, oh good times. When I was twelve we went to a relative's house for a visit, little did I know my cousin brother had a PS2, I found out by sneaking into his room because he was out with friends. This was almost towards the end of the PS2's life cycle though, and his was a first generation humongous one, most of his games didn't work anymore, but this title did.
PC: Hoho.. my Sister had a (then bleeding edge, now 20+ year old piece of junk) PC. Anthlon GPU, 512MB of RAM, 40GB HDD and I don't even remember what GPU. One day I just got curious so I sneaked into her room and turned it on (I think you probably start noticing a pattern here

, I swear I'm not a bad boy D

. She only had one game installed, Warcraft 3, and the Frozen Throne, with V5.5x of Dota-Allstars IIRC. WOW! Just WOW! This was the best gaming experience I'd ever had in my whole life up till then, and till now few titles manage to actually surpass it. So began the days of sneaking into her room when she wasn't around and loading up that saved file of mine to continue through the campaign, I really had so much fun, I dabbled a little in Dota, but because I was playing alone, didn't see the point back then.
Gameboy Advance SP: Final Fantasy VI. Yes yes another gameboy, these things are damn popular where I live, even till now.
Xbox 360: Resident Evil 5. 4 years ago. I was so happy, this was my true first system, all the ones before didn't belong to me, but eventually became gifts from my cousins and my sister. This was when I got my first taste of last gen, the first time I was actually up to date with the latest games instead of scouring the net reading about obscure titles which came out decades ago. As a result, RE5 for all the lambasting it has received, holds a special place in my heart.
Present day, modern PC: Brothers, A Tale of 2 Sons. Not much to say about this one.
There, that's all for my rambling, I already tried keeping it short, guess I really can't shut up.