Posted: May 2, 2016 A boardgame with hidden movement using the Battleship approach of separate, secret boards.

Fig 214.1 - Ninja Battleship.

I was playing Battleship with my kids and I thought, why hasn't this sort of thing been done in other games? So I decided to come up with a Battleship-like idea that is a boardgame with hidden information, with each player having their own board. And when I think of hidden information, I think ninja.

That basic premise is that each player has a board upon which a treasure is placed (known to both players). Using their ninja, they must sneak onto the opponent's board, steal the treasure, and return to their board. So, it's kind of like capture the flag. The twist is, the ninja's position is only known to the controlling player - for the most part.

There are three guards that each player controls that can only move around on their own board. Their positions are public knowledge, so you would say something like "Guard #3 to E6". Guards move like Rooks in Chess, where they can move in a plus shape any distance. So they can cover ground quite quickly, but only in a straight line. The ninja can move 3 or 4 spaces in any direction, so they can slink around corners.

Each guard can also see in a plus shape, and any time a player wants to move their ninja through the guards' sight line, he must tell the other player. Like "Moving my ninja, he is spotted at E6 and E7, then disappears". The opponent now knows where the ninja was, but not which direction it moved or how far. Similarly, the player must announce when the treasure has been taken, regardless of whether any guards can see it.

Players alternate, moving one piece at a time. If they focus on moving the ninja too much, the guards will be easy to sneak around. If they move the guards too much, their own ninja will make little progress on capturing the treasure. Ninjas can be captured (with that player losing) by moving a guard onto their square, and one can corner an opponent's ninja with the guards to keep them from escaping.

Similarly, ninjas can defeat guards by landing on them, so long as they are only seen immediately next to the guard. You can't just run down a hallway at the guard, but you can sneak around a corner and take them down. Guards are returned to the game after a turn or two, so killing a guard doesn't remove them completely, but can open up temporary paths through the opponent's zone.

The one big problem with the idea is that a player which just camps the treasure chest with his three guards is at a distinct advantage. Perhaps some sort of once per game smoke bomb ability which allows the ninja to move one turn without being spotted at all, or maybe some sort of distraction ability which lets the ninja announce his position briefly to draw the guards away from the treasure. Another ideas are doors that can be opened or closed, which allows the ninja to block line of sight by announcing his presence near a door.