A simple introduction
The game is played with four balls, Blue and Black versus Red and Yellow. Each turn consists of just one shot, and play is strictly in sequence: Blue, then Red, then Black, Yellow and Blue again. The order of the colours is shown on the peg in the centre of the court.

All four balls attempt to get through Hoop 1. As soon as one ball is successful, that side scores a point, and attention passes to the next hoop in the sequence. The first side to seven points is the winner.
Hitting the opponent out of position is legal. Players will often clear an opponent’s ball 30 yards, in the hope of keeping it out of range. Tactical complexity arises out of blocking shots, and putting the other players out of position, while putting your partner into a better scoring opportunity.
Read More Rules
More detail available in the Basic Rules of Golf Croquet here.
The definitive rules of Golf Croquet are available from The World Croquet Association. These rules were revised and came into effect on 1st March 2019. Although they do not change the way the game is played, they are supposed to clarify the language!
https://worldcroquet.org.uk/documents/Governance/GCRC/WCF%20GC%20Rules%205th%20Edition.pdf