From SuspireWiki

General Darts

The rules of Darts are easy. You get three darts in hand and you try to get the most points as quickly as you can, up to a total amount (500, usually, though some people prefer 250). Each round consists of both people tossing all five of their darts at the dartboard.

Darts, Quick Rules

Pros: Short and dirty, no one will hate you for spamming their channel with rolls.

Cons: Not a very realistic representation of Darts.

Dexterity + Athletics

First Person to 10 successes wins.

Darts, Longer Rules

There's none, use the Quick rules.