I saw a similar thread while searching but it was almost 2 years old and archived so I figured why not start one similar?
For me, I started off old-school with Nintendo 64, moved to playstation 1, then PS2, then finally 360 in August 06'. Played a bit of Command&Conquer on PC when I felt like it.
Pretty sure Spryo was my first game on PS1, and Crash: Wrath of Cortex first on PS2. Killzone 1 was my first ever online game on PS2. Battlefield 2: Modern Combat was my first online game on 360, then Gears of War 1. Got into Call of Duty once 4 came out and got pretty good ran with good team for a long time.
Got the achievement itch in my alone time playing games when I wasn't playing matches with others. And kept playing games I wanted to in spare time when I could and here I be, awaiting the next arrival of fall games like every past year.