Couch co-op is big in our family. SpiderHeck, Don’t Starve Together, BattleBlock Theater, and plenty of others have been part of it. Xbox is still a big part of our house.
When we wanted several Minecraft players on one Linux box and one TV, I wrote a window manager so each controller could have its own part of the screen.
My youngest has reached the point where I can barely beat her, if I beat her at all. We play SpiderHeck almost every day lately, and she seems to win most of the time even when her older brother is playing. He is already scary enough.
She caught me off guard years earlier. I let her play Skyrim when she was young enough that I did not expect her to get very far. I left the room for a little while. When I came back, she had found a powerful dragon and was kiting it through the window of what I remember as a church. It had about a quarter of its health left.
She finished it. I asked what she was going to do next. She collected the loot and said she was going to find the next one.