I'm aging myself here.
The first game I really played (aside from my granddads super old Pong console) was Sonic the Hedgehog on my Sega Master System II.
Don't remember much of it, but I know this: I never played a Sonic game since. I guess it just wasn't for me.
What about you?
My grandad had a Vic20. I don't really remember the games, I was young, but I do remember we put code in from a magazine and it was a game of gorillas throwing bananas at each other.
Proper gaming began when he got a c64 and played games like Kick Start, Kane, Joe Blade, Battle Valley, Boulder Dash, Druid, Dizzy. Loads more. He gave me the c64 a year or so later and it was so amazing!
After that I got a Mega Drive then an Amiga 500+.