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Overview
inZOI tracks time through a day-night cycle, a four-season rotation, and a life stage aging system. Each in-game day progresses from morning to night, seasons change every 7 days, and Zois age through 9 life stages over the course of 100 in-game days. Players can throw birthday parties as social events to celebrate aging milestones, and a dedicated calendar system is planned for a future update to add structured event tracking and birthday scheduling.
Day Length Settings
The length of one in-game day can be adjusted in Settings > Simulation > Length of Day. This setting controls how quickly real time translates into in-game time, which affects how fast aging, seasons, and daily routines progress.
Setting | Real Time per In-Game Day | Notes |
|---|---|---|
48 minutes | 48 min | Fastest option; aging and seasons progress quickly |
90 minutes | 1.5 hours | Default setting; balanced pacing |
4 hours | 4 hours | Slower pace; more time per day for activities |
24 hours | 24 hours | Real-time; one real day equals one in-game day |
Changing day length affects how quickly time passes during gameplay but does not change the total number of in-game days in a life stage. A Zoi who lives for 100 in-game days will always live 100 days regardless of the day length setting. The playback speed controls (1x to 4x) at the bottom-left of the screen provide additional time acceleration on top of the day length setting.
Seasons
inZOI features four seasons: Spring, Summer, Fall, and Winter. Each season lasts 7 in-game days. At the default 90-minute day length, a full season takes approximately 10.5 hours of real time. A pop-up notification announces the start of each new season.
Seasonal behavior differs by city. Dowon experiences all four seasons with noticeable temperature shifts: warmer summers and colder winters. Bliss Bay maintains a warm climate year-round, reflecting its Southern California inspiration. Cahaya has a tropical climate without cold winters.
Temperature changes affect Zoi behavior and health. Zois automatically adjust their clothing based on the current temperature. Wearing clothing not suited to the weather can cause illness, requiring a First Aid Kit to recover. Players can manually change the weather through the Edit City menu, though manual changes revert to the default seasonal weather after one in-game hour.
Life Stage Durations
Zois age automatically as in-game days pass. Each life stage lasts a set number of days:
Life Stage | Duration (Days) | Cumulative Days |
|---|---|---|
Newborn | 1 | 1 |
Toddler | 2 | 3 |
Child | 7 | 10 |
Adolescent | 5 | 15 |
Teenager | 4 | 19 |
Young Adult | 10 | 29 |
Adult | 20 | 49 |
Middle-Aged | 16 | 65 |
Senior | 35 | 100 |
A Zoi's total natural lifespan spans 100 in-game days from Newborn to the end of the Senior stage. Players can disable aging entirely in Game Options > Simulations (added in v0.1.4), or speed up aging by reducing the day length.
Birthday Parties
Birthday parties are a type of social event that players can organize to celebrate a Zoi's aging milestone. To throw a birthday party:
Open the Smartphone (P key) and tap the Events app.
Find an open time slot on the Zoi's schedule (minimum 2-hour block).
Select Make Event and choose Party as the event type.
Name the party, set its duration, and choose a location.
Invite up to 10 guests, set the dress code, and choose recommended/prohibited activities.
Decorate the venue before guests arrive for a smoother party experience.
During the party, an activity list appears with optional tasks including greeting guests, lighting candles on the birthday cake, and taking a group photo. Guests arrive automatically once the event starts. Completing these activities enhances the party experience, though they are not mandatory.
Party Customization
When setting up any party, you can configure which activities guests are encouraged or prohibited from doing:
Indoor: music, TV, bathing, repairs, sleep, cleaning
Food: eating, cooking, coffee
Hobbies: instruments, dancing, writing, games, reading, workouts, photos
Conversation: hugging, kissing, romance, fighting, rudeness, kindness
Planned Calendar Feature
A dedicated in-game calendar system is listed on the 2026 Roadmap for a future update. The calendar is expected to add:
Visual calendar tracking days, weeks, and seasons
Birthday assignments for all Zois with advance notifications
Event scheduling and reminders integrated into the calendar view
Integration with seasonal events and holiday festivals
A progress indicator showing how close each Zoi is to their next life stage
Currently, there is no way to see a Zoi's exact birthday or how many days remain until the next age-up. The planned calendar feature is intended to address this community request. Check the Update History for the latest patch notes on when this feature launches.
Related Features
Time and Seasons: detailed weather and seasonal mechanics
Life Stages: full breakdown of each age group's abilities and restrictions
Social Events: how to plan parties, dates, and weddings
Memory System: birthday memories as life milestones