Scientific Design, Kungratz Private

1. Purpose of this page

Kungratz was not built as a general reminder app that happens to be usable by older people. It was designed from the ground up for the elderly and for people living with the visual, motor, cognitive, hearing and neurological conditions that become more common with age. Almost every visible design choice, the colours, the type, the button shapes and placement, the way the alarm behaves, traces back to a specific condition it is meant to accommodate.

This document serves two purposes:

It sets out, decision by decision, the design choices made for elderly and vulnerable users, the design, its purpose, and the scientific or standards-based reasoning behind it. This is the evidence base for the “designed with the elderly in mind” section of the website and the app.
It provides the clinical justification for the sensitive Android permissions Kungratz requests (exact alarms, the battery-optimisation exemption, and re-scheduling after a restart). App stores review these permissions closely; this document shows why, for this audience, an ordinary notification does not work and these capabilities are the app’s core function rather than a convenience.

2. Who Kungratz Private is designed for

Kungratz is an adults-only (18+) application, designed with particular care for older users and their families. The conditions it deliberately accommodates fall into five groups:

Vision, presbyopia (age-related long-sightedness), cataracts, glaucoma, age-related macular degeneration (AMD), reduced contrast sensitivity, and acquired colour-vision decline.
Movement and dexterity, Parkinson’s disease, essential tremor, arthritis (osteo- and rheumatoid), and general loss of fine-motor control.
Memory and thinking, age-related memory decline, mild cognitive impairment (MCI), and dementia including Alzheimer’s disease.
Hearing, presbycusis (age-related hearing loss).
Neurological / photosensitivity, the risk of photosensitive seizures.

Why this matters at scale: the World Health Organization estimates that at least 2.2 billion people live with a vision impairment, that around one in three people over 65 are affected by disabling hearing loss, and that more than 55 million people live with dementia worldwide, figures that rise steeply with age. Designing for these conditions is not a niche concern; it is the reality of the ageing population Kungratz serves.

3. The design decisions

Each table below groups the decisions by the group of conditions they primarily serve. Many decisions help across several groups (large high-contrast type helps low vision and cognition alike); they are listed under their main purpose.

A. Seeing the screen: vision (cataracts, glaucoma, AMD, presbyopia, low contrast sensitivity)

Design decision	Purpose	Reasoning & scientific basis
Warm off-white canvas (#FDFBF6) used everywhere, never a harsh pure-white screen.	Presents all text and colour on a soft, low-glare background for cataracts, presbyopia and reduced contrast sensitivity.	The ageing lens and cataracts scatter light and cause glare, turning a pure-white screen into an uncomfortable glare source. A warm, very slightly dimmed canvas cuts glare while keeping text contrast extremely high. (The canvas was lightened further at the request of a real elderly user who found the earlier cream too dark.)
Deep navy text on the cream canvas, measured at 8.5:1 contrast.	Maximum legibility for AMD, glaucoma and reduced contrast sensitivity.	WCAG 2.1 asks for 4.5:1 (AA) and 7:1 (enhanced AAA, SC 1.4.6) for text. Navy-on-cream exceeds the enhanced AAA threshold, so text stays readable as contrast sensitivity declines with age.
Bold-only typography: body text is never smaller than 20sp; headings are 24-26sp; regular weight is not used anywhere.	Larger, heavier letterforms for failing near-vision and central-field loss (AMD).	Heavier, larger letterforms carry more stroke contrast, which aids reading when contrast sensitivity is reduced; the app enforces a bold minimum and never uses regular weight in the interface.
A fixed palette of 13 highly-saturated, distinct colours, each with a verified black-or-white text pairing.	Colours stay distinguishable despite age- and disease-related colour-vision decline, and meaning is never carried by colour alone.	Ageing and glaucoma degrade blue-yellow discrimination. The palette relies on large blocks of high-luminance-contrast colour, always paired with a checked text colour, and never uses colour as the only signal (WCAG 1.4.1).
The alarm shows a large 120dp circular contact photo and the person’s name in 24sp bold.	A recognition aid, who is this reminder about, legible at arm’s length.	A large face plus a large name supports recognition (which is easier than recall) and remains readable for low-vision users without glasses.
The saved message (“wishes”) appears in a high-contrast white card in large bold text.	Makes the thing to act on unmistakable.	Isolating the key content on a white card at maximum contrast reduces the visual search effort for low-vision and cognitively-impaired users.

B. Using the buttons: movement & dexterity (Parkinson’s, essential tremor, arthritis)

Design decision	Purpose	Reasoning & scientific basis
One uniform large pill button everywhere, 55dp × 180dp, fully rounded, 22sp bold label.	A generous, consistent touch target for arthritic or tremoring hands.	The target comfortably exceeds the 48dp minimum touch target recommended by Android / Material accessibility guidance and aligns with WCAG target-size guidance (SC 2.5.5), reducing mis-taps caused by reduced fine-motor control.
Buttons are laid out in a staggered zig-zag, alternating left and right of the centre line, always starting top-left, with a wide empty gap down the middle.	Stops an involuntary movement from striking the wrong button.	For Parkinson’s disease and essential tremor, placing consecutive controls on opposite sides with dead space between them means a tremor is far less likely to land on the adjacent action. This is written into the app’s single button standard as an explicit “anti-mistap” rule.
Destructive actions (Delete) always sit furthest from the primary action, and the red “Back” control is always the bottom-most button.	Guards against accidental destructive or navigational taps and keeps every screen predictable.	Separating the “go” action from the destructive one is a standard error-prevention pattern (WCAG 3.3.4), doubly important where tremor and slower reactions are common.
A firing alarm is dismissed ONLY by a deliberate on-screen button tap, never by a stray touch anywhere else on the screen.	A fumbled grip or a resting palm cannot silence or dismiss the reminder.	Elderly users often pick a phone up awkwardly. Requiring an explicit, labelled action to dismiss protects the entire purpose of the reminder from an accidental touch.
Every screen keeps its buttons clear of the system navigation bar and scrolls when needed, so no button is ever hidden or overlapping, even at very large font sizes.	Every action stays reachable regardless of the user’s chosen (often enlarged) font size.	Older users frequently set the system font large; the layout adapts rather than pushing controls off-screen or under the nav bar where they would be mis-tapped.
Reminder-only: the app opens an empty chat with the person and invites a voice note or video, it never types or sends for you.	No typing is required to reach out, helpful for arthritis, tremor, low vision or low literacy.	Speaking a message is far easier than typing on a small keyboard for the target user, and it keeps the real human voice in the greeting.
Setting a reminder uses contact type-ahead, tappable occasion chips and a slimmed 5-step wizard.	Minimises the amount of typing and the number of steps needed.	Reducing text entry and step count lowers both the motor and the cognitive burden of setup.

C. Remembering how it works: memory & thinking (memory decline, MCI, dementia)

Design decision	Purpose	Reasoning & scientific basis
Each function has its own fixed colour, used consistently everywhere (green = go/send, red = back/stop, amber = remind me, and so on).	Users can recognise an action by its colour without having to read it, recognition instead of recall.	Memory impairment and dementia spare colour and shape recognition longer than text recall. A stable colour-to-action mapping lets a user operate the app from their memory of the colours.
A deliberately repetitive, predictable layout, the same controls in the same places on every screen.	Consistency reduces the effort of re-learning each screen.	Predictable, low-variation interfaces reduce cognitive load and disorientation for people with MCI or dementia.
When a recurring reminder has fired, it shows a green “Done, you remembered” marker and does not vanish.	Reassurance that the task was completed; avoids the “did I already do it?” anxiety loop.	For dementia, a persistent positive confirmation prevents repeated re-sending and the distress of uncertainty. An event that simply disappeared would remove that reassurance.
The app never sends anything automatically, it only reminds; the person always makes the final send.	Keeps the user in control and the greeting genuinely theirs.	A memory aid that prompts rather than acts keeps agency with the person. It also avoids the confusion of auto-sent messages the user does not remember sending.
Setup uses plain language, few steps, and a neutral date-of-birth age check with an elderly-friendly “I entered it by mistake” recovery.	Nobody is locked out by a confusing gate or a slip of the finger.	Forgiving, reversible flows respect the slower, more error-prone interaction typical of older users.

D. Hearing the alarm: hearing (presbycusis)

Design decision	Purpose	Reasoning & scientific basis
The reminder arrives with a sound the user picks for themselves during setup, played on the phone’s notification channel at the phone’s own notification volume.	An alert the person has chosen and can actually hear, rather than a fixed tone chosen for them.	Presbycusis affects the high frequencies first, so a tone one person hears clearly can be inaudible to another. Letting the user choose the sound means it can be set where that person still hears well. ⚠ It is deliberately not put on the alarm stream: an earlier version did that and it was removed, because a birthday reminder must never override the phone being on silent during a hospital visit or a funeral.
The phone vibrates when the reminder arrives, alongside the sound.	A felt signal for users with significant hearing loss.	Multimodal alerting, sound and vibration together, means the reminder can be noticed through either channel.
The reminder is posted at high importance, so Android shows it as a banner at the top of the screen rather than only in the notification tray. It can be dismissed like any other notification, and on the lock screen it appears without naming the person.	Seen even when it cannot be heard, without taking the phone over.	A prominent on-screen notice covers the case where the sound is inaudible. ⚠ An earlier version answered this with a full-screen takeover over the lock screen. It was removed, along with the two permissions behind it, in favour of a notice that is prominent rather than intrusive and that respects the phone’s silent and Do Not Disturb settings. Naming nobody on the lock screen keeps the person’s identity private to anyone who picks the phone up.

E. Safety from seizures: neurological / photosensitivity

Design decision	Purpose	Reasoning & scientific basis
The alarm’s colour animation is a slow, smooth gradient that drifts through the palette, about one colour every 3 seconds, a full cycle every 24 seconds. It never blinks, flashes or strobes.	Celebratory colour with no seizure risk.	Photosensitive epilepsy can be triggered by flashing faster than about 3 flashes per second (WCAG 2.3.1). This animation changes at roughly 0.3 changes per second, about a ten-fold safety margin, and the code carries an explicit warning never to speed it up without re-checking the guidance.
No flashing anywhere in the app; every transition is a smooth fade or drift.	A blanket no-strobe rule across the whole product.	Removing all strobing eliminates photosensitive-seizure risk everywhere, not only on the alarm screen.

F. Making sure the reminder actually reaches the user: reliability

This last group of decisions is what makes the reminder dependable for someone who cannot afford to miss it. It is also the direct reason for the sensitive permissions justified in Section 4.

Design decision	Purpose	Reasoning & scientific basis
Reminders are scheduled as exact alarms that fire at the set time.	A birthday greeting has to arrive on the right day, at the right time.	Inexact or deferred alarms, which the operating system may batch hours later to save power, would defeat the purpose. This requires the exact-alarm capability (Section 4).
When it fires, the reminder uses a sound the user chose during setup, and one tap opens the whole occasion in large, calm type.	The elderly user actually notices it, and can act on it without hunting.	Standard pop-up notifications are transient and are routinely missed by older, low-vision or cognitively-impaired users. An earlier version answered this with a full-screen takeover over the lock screen. That was removed, along with the two permissions behind it, in favour of a reminder that respects the phone's silent and Do Not Disturb settings: it must never shout over a hospital visit or a funeral. The notice is made noticeable instead by a sound the user picks themselves, by naming the person rather than the app, and by opening onto one large uncluttered screen (Section 4).
The alarm fires reliably even when the phone has been idle for a long time or aggressive battery-saving is active.	The reminder is not silently killed by the phone.	OEM battery managers (notably on Samsung, Xiaomi and OPPO devices) suspend background apps and can drop scheduled alarms. A battery-optimisation exemption is needed for dependable delivery (Section 4).
All reminders are re-armed automatically after a reboot or a clock / time-zone change.	No reminder is lost because the phone restarted or the user travelled.	This requires the receive-boot-completed capability, with a daily safety re-check as a backstop.

4. The clinical case for the sensitive permissions

For app-store reviewers. The permissions below are the ones app-store reviewers scrutinise. Each exists solely to make the reminder dependable and unmissable for a vulnerable user. For this audience, the ordinary alternative, a small, transient notification, demonstrably fails: it is missed by users with low vision, hearing loss or memory impairment. That is the same “core function, not convenience” necessity test the stores apply to exact-alarm declarations, and Kungratz meets it. ⚠ The app does not use a full-screen intent and does not request “display over other apps”: it was redesigned so that neither is needed.

Permission	Why Kungratz needs it for the elderly	What fails for the user without it
SCHEDULE_EXACT_ALARM	Fire each reminder at the exact date and time it is due.	Android may delay the reminder by minutes or hours to save power, so a time-specific greeting arrives late or on the wrong day.
REQUEST_IGNORE_BATTERY_OPTIMIZATIONS	Ask to be exempt from battery optimisation so scheduled alarms are not suspended.	OEM power management can silently kill the pending alarm, and the reminder never fires at all.
RECEIVE_BOOT_COMPLETED	Re-schedule all reminders after the phone restarts.	Every pending reminder is lost on reboot until the app is manually reopened.
WAKE_LOCK	Briefly wake the device so the alarm can sound and show.	A sleeping phone may not raise the alert at the moment it is due.
POST_NOTIFICATIONS	Show the reminder on Android 13 and newer.	The operating system suppresses the app’s alerts entirely.

Requested responsibly. Each of these is requested in context, with a plain-language explanation, at the moment it is needed, not silently at install. The exact-alarm capability, for example, is requested at runtime rather than auto-granted, precisely so the app is honest about what it uses and why.

What Kungratz Private deliberately does NOT do

The counterpart to asking for these capabilities is restraint everywhere else:

Your reminder content, names, dates, photos and the messages you write, stays on your device. The single exception is a small encrypted safety copy carried by Android's own backup to your own Google account, so a lost phone does not erase everything. It deliberately contains no names, and we never receive it and cannot read it.
The app never sends a message automatically. You always make the final tap to send, in your own words or your own voice.
Contacts and Calendar access are optional and requested only on demand, are read-only, and the calendar read is filtered to birthday and anniversary events only.
The app declares no camera, microphone, telephony or SMS permissions.
The app no longer takes over the screen. An earlier version showed a full-screen alarm over the lock screen. It was removed, along with the two permissions behind it, so a reminder is now an ordinary notification that follows your phone's silent and Do Not Disturb settings.
On the free version the app shows one advertisement, and it is ours, built into the app itself. No advertising network is involved, nothing is downloaded to choose it, no advertising identifier is read, and the app has no ability to determine your location. A subscription removes it. The permissions above are never used for data collection.

5. Evidence base

The design decisions above are grounded in recognised accessibility standards and in peer-reviewed research on age-related conditions. Every source listed here was individually read and checked to confirm that it supports the specific point for which it is cited.

Every link below was verified working (permanent DOI or official source where available). The full citations appear under each section below, so every claim carries its own visible proof; the complete audit trail is in the Appendix.