I've played GOIO for about a year now, and I still find things that I didn't know about the game.
For example, just now, I discovered that, when you are on the ship-screen, you can press your movement keys (wasd) to rotate the ship, such you can examine the bottom of the ship.
I feel like my words aren't doing justice. I'm kinda mind blown to write correctly. Try it for yourselves, go to ship-screen and press your movement keys.
I bet there are numerous other things that you've learned after having played for a while. Like, b to captain-target spot, the drums when other ships are near, etc. etc. Post'em here!