Round the Clock
Often the first game people learn is Round the Clock. Players alternate turns and must hit each number starting at the number 1 and finishing at the number 20. For instance, player one starts and the first dart hits the number 1. On the second dart the player aims for the number 2 but misses. On the third dart the player aims for and hits the number 2 so when this player starts their next turn the player will be aiming for the number 3. The first player to get to 20 wins.
There are many variations to round the clock. A popular one is if all three darts score the shooter continues to shoot. Another variation is that doubles and triples skip you two and three numbers respectively. For example a player is shooting for 14 and hits double 14, the player now shoots for 16 bypassing the 15 because of the double. One version we often play after getting to 20 in order to win the game the player must finish with either a bullseye or a double 20.