Colour whist (Kleurenwiezen in Dutch) is a Belgian variation to the card game whist.
In contrast to the normal game of whist, the trump colour is determined by a bidding process rather than being the last card on the stack. The trump is determined during a first phase in the game. A player "asks" for a colour, and the next players can pass, join him, ask another colour or ask another game. The colours have a hierarchy: hearts is the most valuable, followed by diamonds, followed by clubs and the spades are the least valuable.
When multiple colours are in the running for the trump, a bidding process determines which one will become the trump. The colour worth the least must always bid one trick higher. The amount to which had been bid is the minimum number of tricks they must win to win the game. The amount of tricks usually starts at five or six if a player is alone and at seven or eight when he has a partner, these specifics are very much subject to change. Partners cannot converse while bidding and only the one that joins can do the bidding. He has the option to "pass parole", allowing his partner to decide. This is however only permitted once the bid reaches 10.
Note that there are as many variant rules as there are groups that play the game.
This is also the hierarchy, a lower game will overrule a higher one.
Some player groups may choose to play without small misery, picollissimo and picollo, as these "special modes" are otherwise chosen too often. Some groups also play without the possibility of re-dealing when all players bid on different suits.
This is all very much subject to change. Everyone uses their own rules.
Note that if a game is 2vs2 each player will win or lose this amount of points. If a game is 3vs1, the one going alone will win (or lose) 3x this amount. This will make sure that the balance of points is always in equilibrium. Also note that doublers (pass, carte blanche and trull) are cumulative (instead of multiplying) e.g. after two pass rounds score is dealt x3, after three pass rounds x4, after three pass rounds and trull x5 etc.