My very first game was a kind of "capture ascii characters on screen" game on my ZX Spectrum where ascii characters appeared moving on the screen and the user had to catch them by pressing some keys on the keyboard. It was very basic (no puns).
I also remember some of the games I wrote that my friends and colleagues really liked. One of them was based on arcade's Polaris in which the player controlled a submarine trying to hit other submarines, ships and airplanes on the Tandy Color Computer. Dude, I wrote those games back in 1987, 1988!
Another game I wrote was a Tron like game (the cycles part) for the PC in 1991. My friends at school lined up to play it and even made me change the game so it would have 3 rounds each match, just like the arcade's new release Street Fighter 2 - The World Warrior. Those days were really fun!