A behavior-driven mobile experience that helps users build lasting routines — one brick at a time.
Most habit-tracking apps focus on streaks and checkboxes — but they don't address why habits break. Users quit not because they lack discipline, but because the apps don't support them when life disrupts their routines. The Habit Stacking app was designed to meet users where they are, using a "brick by brick" metaphor that makes progress feel tangible, forgiving, and worth continuing.
Design a system that keeps users engaged through the critical first two weeks.
Give users a physical metaphor — building a wall of bricks — that communicates momentum.
Introduce a Replacement Brick mechanic so a missed day feels like a pivot, not a failure.
Get users to their first habit logged in under 90 seconds from first launch.
I conducted competitive analysis across five leading habit apps and synthesized themes from 12 user interviews with adults aged 22–40 who had tried and abandoned at least two habit apps in the previous year.
Audited Habitica, Streaks, Fabulous, Finch, and Productive — mapping where each lost users and what gamification mechanisms they used.
Semi-structured conversations exploring habit motivations, failure triggers, and what "success" looked like. Synthesized into an affinity map with 4 major themes.
Defined two primary personas: The Restarter (rebuilding after burnout) and The Optimizer (adding structure to an already-productive life).
Reframed research insights into four HMW statements that guided the ideation phase and kept the team anchored to user needs.
The design system reflects the core metaphor. Colors signal state: Deep Green for active habits, Burnt Orange for replacement bricks, Soft Mint for streaks, and Golden Yellow for milestone celebrations. Every UI element reinforces the feeling of building something real.
Deep Green
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Burnt Orange
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Soft Mint
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Golden Yellow
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Deep Navy
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Each completed habit adds a brick to the user's visible wall. The wall becomes a personal artifact of consistency.
Miss a habit? Log a related micro-action instead. The wall keeps growing — a missed day is never a wasted day.
Chain habits together using anchor triggers. The app guides users through a pairing flow backed by behavioral science.
At Days 7, 21, and 66, the app celebrates with full-screen animations and badge unlocks that feel worth sharing.
Usability testing across 8 participants (2 rounds, SUS scoring) validated the core flows and surfaced several iterations. The Replacement Brick mechanic was the highest-rated feature — nearly every tester called it "the thing that would actually keep me using this."
Given more time, I'd run a longitudinal study to measure actual retention past Week 2. The Replacement Brick system was hypothesized to reduce churn, but real behavioral data would sharpen that story significantly. I'd also explore push notification personalization — timing habit reminders to each user's logged peak-energy window rather than a static schedule.
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