There is a long tradition of playing games of chance during the evenings of the holiday. Originally the dreidel was not connected with Chanukah in any way. The German Christians also had the custom of spinning a top on Christmas eve. The Germans borrowed the game from the Greeks and Romans.
The Dreidel is a four sided top printed with the Hebrew letters:

• nun
• gimmel
• heh
• shin

These letters represent the words "nes godal hayah sham" and translate into "A Great Miracle Happened There."

Everyone in the game starts with 10-15 tokens (nuts, raisins, matchsticks, pennies). Each player puts one of these into the middle (called the pot). The dreidel is spun by one player at a time. Whether he wins or loses depends on which face of the dreidel is up when it falls.

Nun means nisht or "nothing." Player does nothing.
Gimmel means gantz or "all." Player takes everything in the pot.
Heh means halb or "half." Player takes half of what is in the pot.
Shin means shtel or "put in." Player adds two objects to the pot.

When only one object or none is left in the pot, every player adds one.
When an odd number of objects are in the pot, the player rolling heh, "half" takes half the total plus one. When one person has won everything the game is over.