Is It Open World?
No, Onimusha: Way of the Sword is not an open world game. This has been confirmed by Capcom in their interview with Wesley LeBlanc.
What is an open world game?
An "Open World" game, by recent convention, is seen as a game whose progression and exploration are non-linear. Exploration is the main focus of the game, and often all these maps you discover are connected in some way. The main storyline can also be put aside for side quests and doing other activities.
Above is the game, Legend of Zelda: Breath of the Wild, which is considered by many as an "Open World" game. In Breath of the Wild, a lot have finished the game by utilizing shortcuts leading to the last boss right away or by obtaining better weapons earlier on. This goes with the non-linear set-up of an "Open World" game.
Onimusha: Way of the Sword does not have the qualities.
Onimusha has been described as a largely linear game. The areas where you can explore are large and can hold secrets, and you can do many side quests, but the main story mostly follows a linear path.
Different Maps
| Kiyomizu-dera Temple | Oni Refuge |
|---|---|
 |  |
Onimusha also features different maps to explore. The demo shows both Kiyomizu-dera temple and Oni Refuge. Both have their own maps. The path is still linear in order to reach your goal in the Main Story.
Related Guides
Game Overview
| Game Overview | |
|---|---|
| Is it Open World? | Combat System - Is it Soulslike? |
| Is it Multiplayer? | Is there Cross-Progression? |
| Is it Steam Deck compatible? | Is there Character Creation? |
