Snakes And Ladders is most likely the most simple and well-known children's game ever. Dating from ancient times not a lot is known about its history but it remains popular with children to this day.
The game is played on a 10x10 checkered board, each square being numbered from one to one hundred. The object of the game is to simply get to the one hundredth square.
Each player takes it in turns to roll a die, and move their counter (usually a tiddlywink) along the rolled number of squares. If the counter ends up at the bottom of a ladder, the player moves the counter up to the top of the ladder, cutting out entire rows of the board. If the head of a snake was landed on, however, the counter would have to be moved to the bottom of the snake, causing a major setback.
Snakes and ladders can be played by just about any number of players (although it's almost always two) and play continues until all but one player has reached the one hundredth square.
Historically (mainly during the 19th and earlier 20th century) the heads of the snakes would be accompanied by a child performing some selfish or naughty act, and at the bottom of the snake would be the consequences of such an action. Similarly the bottom of ladders would be illustrated with a kind deed and the top would be the reward gotten from it.