My favorite is how the Sub can move around while submerged. The spark for this idea originally came from my son, Seth, who has been my main tester and idea man with this game. During an early test, he said “what if the submarine could actually go below the surface of the board and you didn’t know where it would come up again.” And that was all it took for me to get the idea of “stealth markers” going.
When a Sub is submerged, its potential position on the board is indicated by Stealth Markers — little peg pawns. More of these markers can be added to the board to grow the number of possible positions that the sub could resurface at. When it’s time to resurface, the Sub can be placed anywhere there are markers on two adjacent spaces.
The Sub is able to move more quickly underwater, and usually gives you more possibilities than your opponent can cover with his Boats. However, the Stealth Markers can be removed from the board by Boats and the other Sub moving onto the space a marker occupies. If all of the markers are removed from the board, your Sub is forced to resurface and its location is chosen by your opponent.
Also, you can’t fire Torpedoes while in stealth mode. Oh … the Torpedoes are pretty cool too — but I’ll save that for another post.