When I had my first computer capable of video games, an Atari 800, I wrote a very simple game, which I dubbed "Kill the Cities". It laid out a three by three arrangement of red and green rectangles, which were the cities. To destroy a city, you had to shoot it. The cities were in plain view, did not move, did not have shields, and did not shoot back. You had unlimited shots. The only tricky part was the aiming cursor code was rudimentary, and erased anything under it. So if you took your time and scrubbed over a city, you could eventually render it invisible. Given this immense degree of difficulty, if you somehow managed to destroy all nine cities, the game would produce a hissing sound, and the text:
You win! You hear that? They're cheering for you!
This was actually one of my more popular games.