Hunt the Wumpus, while really only a single-player game, is kinda best played with another person present. Trying to figure out the hard puzzles together can be a great co-op experience.
As a child, growing up when games were very explicit in their themes and goals, Hunt the Wumpus threw me for a loop. Not only is most of the screen blank for most of the time you play, there's very little action, sound effects, or clues as to what you're supposed to do.
The game puts you, personally, into the action as well. They don't tell you that Pitfall Harry is trapped in a labyrinthine cave. They tell you that YOU are. And you're not alone. If you don't keep your wits about you, the Wumpus WILL find you. And when it does, the screen fills with nasty sharp teeth and blood, scaring childhood right out of you and pushing you one step closer to being an adult.
In many ways, Hunt the Wumpus was one of the first RPGs. You controlled an "avatar" of yourself. You explored a dungeon. And the game is very strategy-oriented.
This, my friends, is an incredible game--especially when you consider the following:
It came out in 1980, when precious few games were getting emotional responses out of players.
It stands the test of time and is still fun and challenging today.
Game Title: Hunt the Wumpus
Platform: TI 99/4A
Publisher: Texas Instruments
Release Date: 01st Jan 1980