Retro-Gaming is where you play a computer game (or arcade game) on a modern computer, but where the game is somewhere between old and ancient. Many retro-gamers have Space Invaders, Adventure, Dungeon and a few other classics. The uber Retro-Gamers don't touch stuff any more modern than 1969.
Myself, I've got oolite (a version of Elite - a brilliantly addictive combat/trading game that dates to the mid 80s), xchuckie (A clone of Chuckie Egg - another wonderful 80s game), Dungeon (the predecessor of Zorks I and II), Xtank (Car Wars has nothing on this!) and Xtrek (a Star Trek-themed kill-everyone-else game).
So, what ancient games do you admit having (and playing)?