is a 1998 stealth video game developed by Acquire for the PlayStation. The debut entry in the Tenchu series, it was published in Japan by Sony Music Entertainment Japan, and by Activision in the West. Following Rikimaru and Ayame of the Azuma ninja clan as they complete missions for their employer Lord Gohda in Sengoku-era Japan, the gameplay involves the player guiding their chosen character through missions, the aim being to remain undetected while either avoiding or quietly killing enemies. Production began in 1996 as Acquire's first project, with the aim being to create a then-uncommon game using only 3D graphics, in addition to focusing on stealth over action. The team faced multiple technical challenges, and director Takuma Endo ended up taking on multiple roles within the production including scenario writer. It met with positive reception from game journalists, with praise focusing on its mission design and focus on stealth. It was also a commercial success, selling over one million units worldwide by 2003, and having estimated sales of five million across all versions by 2019. A sequel, Tenchu 2: Birth of the Stealth Assassins, released worldwide in 2000. Gameplay 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. 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. Each mission starts off with a skippable briefing, then players can equip a limited number of items at an equipment screen. The items include health potions, trail markers, poisoned rice cakes, caltrops, shurikens (throwing blades in Europe), smoke bombs, grenades and land mines. 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. A map of the level is provided for players. 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. 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