Tenchu was one of the first stealth games, but besides that the games had an immediate "cool factor" because of stealth kills and the grappling hook. The first two games in the series had "tank controls", which meant that no matter where the character was on the screen pressing left and right would rotate the character in those direction, and pressing up and down would make the the character go forward or backwards. This was the accepted way for 3D games to move at the time, but by the time the third Tenchu game came out, they changed it so that controlling the character was relative to the camera.
In all Tenchu games your character is very limited in combat. You can attack with a 3-to-4 hit combo but your enemies block often which would make combat a big annoyance. This, as a design choice, made sneaking much more appealing because if you attack an enemy from behind they would die in one hit. Not only that, but the game would play a cool animation of your character murdering the guards with gory detail(gory for the time). In future games they would add different and multiple animations from many angles. At the time of the first two games this was seen as a reward for the sneaking but future games started to give the player additional rewards(similar to Experience Points) that would give you access to abilities(such as extra combos, zooming in, and more stealth moves).
The other aspect of the Tenchu game that gave them an identity was the mobility. Instead of having to run around and line up frustrating jumps(such as the gameplay in Tomb Raider which was a game with similar controls that came out at about the same time.) in Tenchu games you always had access to the Grappling Hook. With the Grappling Hook you could aim at a ledge that you'd like to climb and your character would shoot a line that would zip you up to in a few seconds. Also, the Ki Meter would give you information of where the enemies were. It consisted of a number next to a symbol. The number would represent the distance of the closest enemy and the symbol would represent to mental state of the enemy. The symbols could be ? , !? , or !!. The only one that made the enemies open for a stealth kills was the question mark which meant that the enemy was clueless, but the other two symbol was varying levels of alert and the player would have to wait till the enemies return to the question mark. This feature, along with the Grappling Hook, always made the player feel they had a grasp of the environment.
The story of Tenchu revolves around a Ninja clan named Azuma. It has only two members(as far as we know) Rikimaru
. They serve Lord Gohda
, who has a daughter and a wife that died in Tenchu 2(which is a prequel). Both Rikimaru and Ayame care for their Lord but Ayame specifically cares greatly for their Lord's daughter, Princess Kiku
. The two Ninja are sent on countless mission to serve and to protect from the shadows. They might be ordered to assassinate an evil merchant or to investigate missing people reports. Usually the missions start slow and a bit routine but there's almost always a larger conspiracy going on. In most of the Tenchu games super natural elements also get involved. Tenchu: Stealth Assassins
- The first game in the series and it has Rikimaru and Ayame fighting against Lord Mei-Oh
. A demon lord with an army. All the major characters get introduced including Onikage
. At the end after they defeat Mei-Oh the cave in which they battled against him begins to crumble and Rikimaru seems to sacrifice himself to save Ayame and Princess Kiku. Tenchu 2: Birth of the Assassins
- The second game is actually a prequel and it shows how Rikimaru became the leader of the Azuma Ninja. They introduce Tatsumaru which is depicted as a brother to Rikimaru and a love interest for Ayame. The game also reveals Onikage's origin as a ninja of the Burning Dawn named Suzaku. Tenchu: Wrath of Heaven (Tenchu 3)
- This game picks up where the first one left off. We find out that Rikimaru did not die at the end of the first Tenchu game. Ayame and Rikimaru have to fight Tenrai, who is a sorcerer thats trying to bring back Lord Mei-Oh. Tenchu: Shadow Assassins (Tenchu 4)
- The fourth game is the first to feature Onikage as the main villain.