Be completely honest... list all the games that really "impacted" you
I don't care what genre, what system, arcade or PC even, as long as it's a video game and it made a big impact on you and how you looked at games, then list it.
Be honest and even if you have a "guilty pleasure" game on your list, list it. Make it as authentic as you can.
It can be as old as Pong, and as new as Ikaruga.
I hope to see everyone's list. You don't have to explain the game's importance to you, but if you wish, be my guest.