The basic objective of One Piece Mansion is simple. Every resident in the player's mansion has a stress level, which is indicated by a small bar above their head. If this level gets too high, they will eventually move out of the mansion.
Every resident affects the stress levels of the residents around it, in both positive and negative ways. Each resident has a unique stress effect, some having negative to the left, positive to the right, etc. The task as the player is to arrange these so that all the residents are happy. However, if a resident does become stressed out, their effect on other residents changes. For example, sweet Ai-Chan radiates stress-reducing arrows to all rooms around her. However, if she becomes stressed out herself, her effect on other residents weakens.
Polpo, the manager, also has a role to play in the game. By switching to manager mode, he can roam around the mansion and perform two important tasks:
- Blow his whistle to send any Syndicate 5 members on that level back to their rooms.
- Use his fire extinguisher to put out any fires in the mansion.
When the mansion becomes full, the player must build new rooms. If all the current levels are full, the player must also expand the mansion upwards with elevators. Building new rooms may also require demolishing elevators. Both construction and demolition require money.
One Piece Mansion can be played in several different modes, each of which have their own unique challenges.
This is the mode in which the plot is followed. There are seven stages of increasing difficulty, with each stage requiring different conditions to be met.
Every few stages, a powerful rival character appears. The rival character will move into the player's mansion and kick out all the trouble residents, leaving the player to deal with him instead.
In Endless Mode, the player is left to develop the mansion at his or her own pace. It allows the player to experiment with new resident combinations and to expand the mansion as far as he or she wishes.
The storyline of One Piece Mansion revolves around a successful landlord called Polpo. At the start of the game, Polpo's little sister is kidnapped by the owner of a rival mansion, Chocola. It is the player's job to battle through levels meeting Chocola's objectives and to eventually free Polpo's little sister.
- Polpo - The mansion manager. Polpo stays busy solving the residents' problems and defeating criminals. His troubles never seem to end.
- Ai-Chan - The sweetheart. Her smile makes all those around her happy.
- Mee - An inquisitive alien resident. He annoys other residents with his blinding laser.
- Osuzu - She lives in her roomful of cats. Her pets' effects depend on how stressed she is feeling.
- Ope - A mysterious doctor. He eases residents stress with his comforting medicines.
- Heebee - A a bamboo craftsman with a stick of live bamboo on his head. When he gets excited, the bamboo sprouts and causes trouble to the residents above him.
- Kiwi - A member of the dangerous Syndicate 5. He burgles the other residents, leaving them broke and unable to pay rent.
The game received "mixed" reviews according to video game review aggregator Metacritic.