There are only only a handful of hidden movement boardgames. Ninja: Legend of the Scorpion Clan (Ninja) is the best hidden movement game. The designer, Frederic Moyersoen, is best known for Saboteur. The backstory is that a ninja is working with a traitor accomplice to accomplish secret missions.
The game plays as follows. The board is an area-to-area movement grid; most areas are adjacent to five or six others, so there is plenty room for maneuver. There are three roles: ninja, traitor, and guards. In a four player game, the guards are split into to two groups. Each player get a paper mini-map that is kept secret. The guard player(s) use the mini-map to mark locations of the hidden mission goals, traps, and sentries, while the traitor and the ninja use their mini-map to plot movement. The ninja and the traitor pawns are only revealed when they are sighted, and disappear next turn.
Once the guards set up, the ninja and the traitor choose a starting location. The ninja starts in a area outside the castle while the traitor starts inside the castle. The ninja is more lethal and has more hit points; the traitor is better at distracting and working without raising the alert level. Since the game is timed, the intruders must reach the mission goals in the inner castle and then escape before time runs out. The faster the intruders move, the more ruckus they create, raising alert level. As alert levels rise, the guard player gets more resources, releasing more guards for search. Each turn the ninja and the traitor move secretly on the mini-map while the guards listen, search, and deduce the location of the intruders. Sneaking around the guards is highly tense. Guards are everywhere and you have to cross their paths, hoping that they do not turn around. The guards, on the other hand, must patiently search, and wait for the intruders to make a mistake. As time runs out, the intruders will rush and make mistakes and the guards must act quickly to corner and cut them.
There are other hidden movement games, but none as elegant, intense, and richly thematic, nor that play in under an hour. It is awesome to see the ninja come out of the shadows, whack someone, and then disappear into the shadows again. Although the game supports up to four players, it shines with two players, is decent for three, and is mediocre with four. By all counts Ninja is must-play game.
