Watching my Dad play Outlaws on the PC in the late '90s. He'd come home from work, we'd go to the park and play, come home, then sometimes he'd boot up the ol' PC and fire up Outlaws. Many of my earliest/fondest memories involve playing on the PC with my Dad or watching him play games. Me and my Dad still play Intellivision a ton because he had the system as a child. I've had a lot of fun with that too. My Dad's not really a gamer, but I'm glad he at least enjoys some of it.
Usually in the Fall, we try to do a season of Tecmo Super Bowl, my Dad'll be the Giants (he grew up in Jersey), I'll be the Broncos (Colorado native here), and my brother is the 49ers because they're the best team in the game. I'm not great at the game, but my Dad and brother get very competitive at it. It's all pretty darn fun.
I'm sorry not everyone's Dad played games with them, but hopefully if/when you have children, you can create gaming memories for them too. Here's to all the great Dads, regardless if they gamed or not.