Key Features
- Believably beautiful Imouto, rendered in high-poly 3D. She could be real.
- Fully simulated Imouto, with more than 50 variable psychological metrics like interests, mood, lust, sexual interest, and more. She IS real.
- According to my estimates, Imouto can adopt more than 30,000,000,000,000,000,000,000,000,000,000,000,000,000,000 (that’s 30 with 49 zeroes) possible personas. These personas are seeded so they remain believable.
- Build Trust and Attraction through a deep dialogue system and actions; lose her trust and sexual interest in you by messing things up.
- Spend leisurely days with your little sister, talking, flirting, bathing and potentially having sex with her (future update) — if she trusts you enough and is attracted to you.
- Get closer together, really…close…together.
- Be a creep and spy on her as she bathes or uses the toilet. Be careful; you might get caught!
- Beautiful “1K Apato” Apartment with day-night cycle.
- Energy, time, money, household management, and other systems were added and planned!
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Game Mechanics (Implemented)
One-handed gaming 
Build Trust
Trust is the most critical aspect of this game. If she trusts you, she will be open to going further. Fail, and she might even decide to call Mom! Most of everything you do when you interact with her is also (co-)dependent on her trust in you. Even if she finds you highly sexually attractive, without trust, she will never dare to confess her feelings to you. The best way to build trust is to talk to her, do fun activities with her, and refrain from doing things she dislikes.
Build Attraction
She will only see you as a big brother or friend without attraction. With enough attraction to you, you may initiate sexual activities, and she won't reject you. Without lust for you, anything of a sexual nature will lead to a swift dismissal...and her losing her trust in you! Low trust, high attraction, and you're just a masturbatory fantasy for her. High trust, low lust, and you're friend-zoned. There is a middle ground you have to find. Building her desire for you can be done through flirting, talking about lewd topics and later by engaging in sexual activity that she finds pleasant.
Interest Matrix
She is modelled with a realistic, comprehensive psychological matrix that is randomised using a seed. This means her exact psychology and interests will differ from playthrough to playthrough! Seeded means it is neither completely random nor set in stone. Each of her over half a googol (10^100) of persona types is believable.
By interacting with her, you can discover her interests and even broaden or deepen her interests.
Discussion Topics
You can build trust by finding discussion topics that strike a chord with her, e.g., that are interesting to her. The higher the interest, the more trust you can build with her. You always get
1 Shared Interest that you can choose at the start of a game. You can find out other
high-interest topics she likes by discussing with her regularly and on various topics. You get to discuss each topic once a day.
Story Events
You unlock Story Events, usually day or weekend trips, by building trust or attraction. These events can increase her trust, lust or mood for the better or the worse. By bonding with her during these events, you can increase her trust in you or desire for you.
Lewd Topics
Sexual interest and attraction can be built by discussing lewd topics. She will naturally be interested in these topics as she's of that age. But, being completely inexperienced, she will take time warming up to discuss these topics openly with Oniichan. Her having high trust in you is paramount, especially when you take those first careful steps.
Mood
Like everyone, Sister has emotions expressed in a general mood. This can be bad, normal, good, happy, embarrassed, etc. Unlike most modern women persons, Sister is well-adjusted, and generally, her mood is normal and stable. Even if she's on her period or not feeling well, her surface mood should be normal most of the time.
But anyone can have a bad day, and your actions can also sour her mood. Luckily, Oniichan can also try to lighten his little sister's mood with games or by cheering her up. Her mood will also influence the trust you can build up from other actions and how receptive she will be to sexual advances.
Menstrual Cycle
She has a menstrual cycle, going through 4 phases on a 21 to 25-day schedule. Her phase in the cycle will influence her mood and her sexual desire. It will also determine her chances of getting pregnant. Certain Oniichans can smell when she's on her period or ovulating. Other Oniichans can try to work out her schedule using the calendar in the room.
Customizable Oniichan
Choose your history with your little sister, each option giving you different advantages and disadvantages when you start a new game. Examples are knowing her favourite discussion topic, having higher trust or attraction, or even knowing when she's on her period.
Career path styles will influence how much money you have to spend and how much time you get to spend with her in the evenings. A student will be home when she's home, giving you maximum exposure time every evening. A part-timer will be home later but has more disposable income to spend on his little sister. Current career paths are:
- Student
- Part-Timer
- Full-Timer
- NEET
- Day Trader (subscribers)
Day - Night and Week Cycle
The game has a perpetual day/night and week cycle. During the days, you'll be at work or at school (or laze around in bed if you're a NEET!). You'll find yourself in her company at home during the evenings. That's when most of the interaction with her happens. Weekends work a little differently since you'll be together all day. That's also when you can enjoy each other's company outdoors and make happy memories together. These activities can cost money but are essential for bonding.
Depending on the scope of the activity, this features a visual novel story with potential extras. PLANNED: specific weekend activities based on specific interests she may have or develop.
Energy Management
Every action costs energy, and you have a finite pool of energy (indicated by your smartwatch battery). You can also regenerate energy through relaxing activities like drinking tea, soda, or bathing. Quality sleep at night is the best way to regenerate a chunk of energy.
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Planned Game Mechanics
I want to include this in the game before I call the Alpha done. This list may change in the exact details or by adding/scrapping ideas altogether.
- Night-time wholesome and lewd interaction (a major part of the game!)
- Nude bathing together with wholesome and lewd interaction (a major part of the game!)
- Additional weekend outdoor activities (an important part of the game).
- Weekend activities are based on her interests (long-term wishes).
- Good and Bad Endings: when she gets pregnant by you, the game ends, and there will be good and bad endings. Good endings involve high trust and having enough resources to make it work.
- New Game+ (either continue after an ending or indeed start over with some inherited benefits)
