Ahoy! Krew.io is a team based shooter game in which you play as pirate canon on a boat. You either start alone on a small raft or with a team and a captain. As a captain you can control the boat, while as a simple crew member you're only allowed to move around and shoot. But that's not an issue because this game is about teaming up. Being stronger when you're with your krew and in a clear disadvantage when alone. When you got your krew together and you're convinced you're strong enough you can start fighting against other ships and try to sink them. But take care matey, you don't want to become shark bait. Once you've won against another you can collect their booty that is now floating on the water. The game allows you to buy upgrades for your ship too, you just have to sail to one of the few islands and sell the loot you got from raiding other ships.
Move around with W, A, S, D, aim with your mouse and left click to shoot at other ships. If you're the captain, which is represented by your canon wearing a little hat, you can also steer the ship by changing your position on the deck.