There are many rules adjustments made by people playing friendly games of croquet. Most are designed to make the game more challenging or exciting.
Dead Ball Option: Players are not allowed to roquet a ball more than once between wickets no matter how many turns may pass. This increases the difficulty, giving players fewer extra strokes.
Poison: This game is usually played cut-throat (no teams). When a player does the complete course, instead of leaving the game, he becomes "poison". When he hits another ball, it goes out of play. When all players are eliminated, the final player left on the field is declared the victor. A twist to this game is that if the poison player goes through a wicket or hits a stake, he himself is eliminated.