How about this as a flash from the past. A version of the game Pong is now available for the Apple Watch. According to Wikipedia, this was the first commercially successful arcade video game machine. Hard to believe these graphics were considered a "video game" based on todays standards for games.
For more information about the $0.99 game, see the article at Engadget. And just for fun, I have included the image from Wikipedia showing the original archade game next to a photo of the game running on the watch.