Green flashes show the opponent has high health, red flashes show the enemy is near death. Also color-coded are the levels of health each opponent has, indicated by a flash when the player strikes or shoots them. As in Bungie's earlier Marathon titles, tiers are color-coded, in this case by green (weakest), blue, and red (strongest). Each class is subdivided into tiers of increasing strength.
There are multiple classes of enemy, each with its own style of unarmed combat. The player can punch, kick, and throw enemies progressing into later levels unlocks stronger moves and combos. Since the player can carry only one weapon at a time and ammunition is scarce, hand-to-hand combat is the most effective and common means of defeating enemies. Power-ups such as 'hyposprays', which heal damage, and cloaking devices, which render the player invisible, can be found scattered throughout the levels or on corpses. There are ten different guns in Oni, including handguns, rifles, rocket launchers, and energy weapons. The game's style was largely inspired by Ghost in the Shell and Akira and shares the same genre, being set in a cyberpunk world.
Originally planned just for the Mac OS and Windows, a PlayStation 2 port was concurrently developed by Rockstar Canada. Gameplay consists of third-person shooting with hand-to-hand combat, with a focus on the latter. Released in 2001, it was Bungie West's only game. Oni is a third-person action video game developed by Bungie West, a division of Bungie.