Tenchu: Stealth Assassins is a stealth video game where players take on the role of either Rikimaru or Ayame, ninja who complete a set of eleven sandbox levels.[1][2][3] While generally similar, Rikimaru has more health but is slower and has only one blade, while Ayame is weaker but uses two blades and has higher movement speed.[3][4] Each mission starts off with a skippable briefing, then players can equip a limited number of items at an equipment screen.[5]: 7–9 The items include health potions, trail markers, poisoned rice cakes, caltrops, shurikens (throwing blades in Europe), smoke bombs, grenades and land mines.[2][3][5]: 12–13 The only permanent item taken into all missions is a grappling hook; when in use, the player enters a first person perspective, and the grapple can be fired at any solid surface to pull the player towards it.[1][4] A map of the level is provided for players.[2]
The selected character's health is shown in the bottom left, with the bottom right showing equipped or found items. Engaged enemies have health bars shown around the top left area of the screen.[5]: 7–9 The goal is to complete levels with minimal detections and disturbances, with most levels ending in a boss encounter, and each having three level layouts which are randomly selected with each playthrough.[1][3] During navigation, the player can traverse rooftops and walls, run or crouch into a sneaking position, hang from ledges, and hug nearby walls to remain undetected. Sneaking up on an enemy undetected allows for an instant kill, with close-range kills triggering cinematic death animations.[4][5]: 16–18 If the selected character dies, the level must be restarted all items aside from the grappling hook are lost.[3]
To monitor surroundings, each protagonist has the Ki meter, indicating the distance and alert status of nearby enemies. A question mark indicates no alert, a single exclamation mark shows enemies are alerted but do not clearly see the character, an exclamation and question mark indicates a high alert state caused by sounds or a body discovery, while double exclamation mark is a full alert state where enemies will attack. A number beside the Ki display shows an enemy's distance.[5]: 7–9 [3] Each mission is ranked from the lowest "Thug" to the highest "Grand Master". Score is impacted by the number of undetected or detected kills, whether the character was spotted, and whether non-combatants were killed. Grand Master rank for each level unlocks a new special ability that can be equipped for replays.[3]
