Walk My Plank is a free online browser based multiplayer game. It's written in such a way that it is playable anywhere you have an internet connection.
The aim of the game is to be better than any of the other pirates. You can achieve this by training your crew, beating up other pirates, exploring the seas, and various other tasks. As you progress through the game you can get bigger and better ships, more cannons, and a bigger, tougher crew.
It's a pretty addictive game, so if you want to see if you have what it takes to be a pirate, sign up and have a go.