Ladder Whist, (aka, Knock-in Whist, Knock-in Ladder Whist and Knock-in Ladders) is a card game derived from Knock-out Whist.
The game was created as a variant to knock out whist and originally called "knock in whist" due to game being created to be the opposite of knock out whist. However, technically one player can be knocked out, if a player loses the first and second rounds. The creators of this game, a group of students, gradually developed new names for the game and considering the game is to progress to 7 cards by obtaining one each round, the name Ladder whist was generally used. However, due to the two names many names of the game have developed overtime. The additional beauty of the game is anyone can join at any time, they simply start at the bottom of the ladder as a dog. This allows for players to leave and join as they wish - ideal for the conditions it was created in, at a college where the students were constantly coming and going. The goal can also be changed so rather than 7 cards required to win you can change the number based on the number of players. Ideally for a lengthy game, worth playing the perfect number of players is between 6-8 with the default goal of 7 cards.
The Aim of the game is to achieve a hand of 7 cards when starting with 1 (known as starting as a dog). Much like knock-in whist, if you have the highest card in the suit first played or the trump card you will win that trick. However if you win the majority of tricks in a round you will then be knocked down to a dog while everyone else will gain an extra card (and climb the ladder towards the 7 cards desired to win). The player who gets knocked down can then select the trump suit for next round. If two or more players win an equal amount of tricks they will all be knocked down and trumps will be selected by the knocked down players randomly selecting a card - highest chosen card acquiring trump selection.