If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Your mission is simple! Eliminate all the pirate monsters you come across in each stage, but be careful with your ammo, it's limited so you only have a few chances to rid the ship of your pirate foe! Make sure you check the whole ship before you start blowing them up, you may need to become strategic as the stages go on. Good luck!