Onimusha: Warlords features pre-rendered backgrounds. The player primarily controls swordsman Samanosuke Akechi in his fight against demons. The game balances its action elements with puzzles that involve interacting with the environments and obtaining items to make progress.
The player begins the game with a standard katana sword, and can obtain long-range weapons with limited supply. As the player progresses, the protagonist Samanosuke can gain three elemental weapons: Raizan, Enryuu and Shippuu, each with an elemental magic attack. As enemies are defeated, they release different colored souls that are absorbed by using the demon gauntlet on Samanosuke's wrist: red souls act as "currency" which can be used to upgrade weaponry, yellow souls recover health, while blue souls recover magic power which is used to perform each weapon's elemental abilities.
Some sections are played with Samanosuke's assistant, the kunoichi Kaede. She has her own distinctive weapons and acrobatic abilities, but is unable to absorb souls.