In the US and many parts of Europe, Cricket is the king of the pub games. Unlike 501, it focuses on strategy and "blocking" your opponent.
The Basics
Players take turns throwing three darts. The goal is to "close" numbers 15, 16, 17, 18, 19, 20, and the Bullseye. To close a number, you must hit it three times (e.g., a treble is an instant close).
Scoring
Once you close a number, you can score points on it as long as your opponent hasn't closed it yet. The winner is the first person to close all numbers with an equal or higher point total.