Touch Grass

We built an Android mobile app that limits your screen time to motivate users to "touch grass" and go outside.

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TOUCH GRASS

Step away from the screen and reconnect with the real world!

Inspiration

Every one of us has lost hours to Reels — even during exam period.

This project started from our experience: escaping short-form and feed addiction, and achieving digital wellbeing, takes more than just capping your screen time. Most of us know what it's like to stay shut inside all day, scrolling social media feeds late into the night. Those are the days we end up feeling drained and tired.

But the moment we actually step outside, something changes. Being out clears your head and pulls you one step closer to the real world. Touch Grass can help you build this habit!

What It Does

Our app helps users step away from the endless feed and refresh loop.

  • Smart App Blocking: Automatically locks a selected app once its daily usage limit runs out.
  • AI-Generated Missions: Uses the Google Gemini API to create challenges that ask you to photograph a real object outdoors.
  • Photo-Based Verification: To unlock, the user has to go outside and take a photo of the requested object.
  • AI-Powered Unlocking: Gemini analyzes the image in real time. If the photo is approved, you can unlock the blocked app and access it!

How We Built It & Challenges

Our goal was to take the idea of "a lock you can only open by actually going outside" and turn it into a fully working Android app within Hackathon. Everything is written as a native Kotlin app, with no separate server — the entire flow completes on the phone itself.

1. Detecting which app is open

Standard permissions cannot tell you when another app opens, so we used an Accessibility Service. It allows how long each blocked app spends in the foreground and compares it against that app's own daily limit (30 minutes by default, editable per app) — so Instagram can be locked while YouTube is still activated.

2. A lock screen you cannot escape

Showing the lock was easy; keeping users from slipping past it wasn't — at first, one tap on Back or Home returned them to the app underneath. We now launch BlockOverlayActivity full-screen, swallow the Back input, and pin the screen with startLockTask() so neither Home nor Recents can reach the app below.

3. Gemini integration

GeminiRepository generates the outdoor mission prompt, then verifyPhoto sends the user's photo alongside that mission text for a verdict. Gemini replies APPROVE or REJECT; a REJECT sends the user back out for another shot.

4. Rebooting issue

AlarmScheduler is an alarm after midnight for MidnightResetReceiver to clear everyone's spent time — but AlarmManager alarms don't survive a reboot, which silently broke the daily chain. We made the same receiver also listen for BOOT_COMPLETED, with both paths checking one shared "last reset date," so a missed midnight is caught on the next delivery instead of lost.

Accomplishments

  • Various missions and easy rerolling: Nothing outside that matches the mission? From the blocked screen, the user can reroll the mission to get an object that's actually within reach.
  • User personalization: We built an intuitive UI/UX with app filtering, category tags, and customizable timers to make the app easier for anyone.
  • Bypass prevention: To stop users from escaping the lock screen through system gestures or app switching, we carefully handled the phone's recents, home, and back behavior to protect the overlay.

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