When I was starting out as a freelance illustrator, I did a few cover designs for Activision and Atari.
Here's what the screen graphics looked like for a game called River Raid, where you fly a jet up a river and shoot at helicopters and ships.
The whole idea with the package art was to develop the 3D fantasy in the player's imagination. I painted the original in oil.
Galaga and Galaxians had arrays of bug-like monsters swarming overhead and dropping bombs on you.
Although there were home versions of the game, you had to play the arcade version to see the latest levels. I wasn't very good at playing the game, so I went to the arcade and offered quarters to the kids who were good at it. I said all I wanted to do was watch them play and sketch the monsters. When I came back the next day there was a whole line of kids with their hands out. Don't know if I would do that now.
Here's one of the oil paintings I did for Galaga. I'm not sure where this turned up in print, but it was fun to paint.
I believe this one was for Galaxians. The painting is in oil, about 16 x 20. Since there was a lot of room for imaginative elaboration, I chose a more comic book look.
A new book is about to be released called Art of Atari.