This game is based on the one made for TI personal computers back in the early 80's. There exists a text MUD-like version on most Unix systems, and I suspect this was the original form of the game. The graphical version is much more fun, however. The rules of the game, to the best of my knowledge, mirror those of the TI version. I'd be interested in hearing of any discrepancies or errors you discover.
The purpose of the game is to locate and kill a nasty man-eating creature called a wumpus. It lives in a maze of interconnecting caverns, letting unsuspecting prey walk into its lair. You have only one arrow, but that's all you'll need - if you don't miss. Unfortunately for you, you can't actually stumble into the wumpus's lair, or he'll eat you. You have to deduce where his lair is and fire your arrow into the lair. If you've guessed wrong, you're a goner.
There are hints you can use to deduce the location of the wumpus's lair. For he's eaten so many people over the years that blood stains the wall for two rooms in every direction out from the lair. This means you are guaranteed to pass through two blood-stained rooms in a row before reaching his lair.
It's still not as easy as you think. There are other dangers in the cavern maze: slime pits. You can avoid slime pits by noticing slime-coated walls, but unlike the wumpus's lair, you only get one room's worth of warning for slime pits.
The board layout is a bird's eye view, revealed as you make your way around. Blood-stained walls are represented by a solid red circle in the center of the room; slime-coated walls are represented by a thin green circle around the perimeter of the room.
Some pairs of caverns are not connected directly, but rather with a twisty passageway. Passageways do not count for the 2 rooms of blood-staining or the 1 room of slime-coated walls, nor do they count for the correctness/incorrectness of your arrow shot. Only the round rooms matter; the passageways are there to confuse your idea as to where the lair or the pits might be.
You may move around using the arrow keys. To draw your bow, press either the Enter key or the spacebar. Then to fire, press the arrow key in the desired direction. If you change your mind about taking your shot, press either the Enter key or spacebar again, and you'll put away your arrow again.
Trial and Error
Your best bet is just to play around and get the feel for the game. A tally underneath the main board will let you know how well you're doing, as well as how many kills the wumpus and the slime pits have claimed. Good luck; may your shot fly true.