You are a ranger on a mission to stop some pirates. The arrow keys move. Up arrow to jump. Space to nock your bow. Click the mouse, the arrow will go to the target. 'T' to throw your throwing knife. 'S' to block a sword swipe or cut open tan barrels with your saxe knife. 'C' to crouch, and hide from your opponents. (The part where you have to get on the boat, you have to crouch when the trader is facing you.)
This is from the Ranger's Apprentice series by John Flanagan. Crowley is the leader. Halt is one of the best rangers alive.