From the designer's website:
This is a game for incredible adventures, fun and relaxing, very undemanding, a game well suited for improvisation. You play a pirate, vile, dirty, unfair, disrespectful and cruel, wandering the Caribbean in search of treasure, alcohol and beautiful women. Pirates do not have an ounce of reflection and throw themselves headlong into the adventure, taking all the risks, regularly receiving memorable blows that would kill an average whale but which merely slow down the pirates. They are superstitious and have a kind of moral code of their own which is usually the cause of crazy situations.
This is a game for those who know nothing about navigation, sailing, geography in the seventeenth century nor anything too serious. There is no real immersion, just the "color" and laughing. Think of it as a pirate movie who will not teach you anything, but will give you a good time. Thanks to the rules, the GM has very little work and will mostly give story primers and hit back the PCs, the game will move on its own. The rules also encourage players to play together, not against each other.
The topic require some maturity, after all it is a question of murder, teasing ladies, drinking, rapine... This is a light and fun caricature of a world which in reality was much darker. Here beatings given or received have little importance, there is no display of blood or guts, just the infantile "bam! you're dead" and "bing! in your teeth." You must also learn to accept the frequent disappointments that your character will suffer.
Pirates! differs from other games on the same theme by the extreme simplicity of the rules, the rather low preparation involved and the tone which is light hearted rather than epic.