OtterDay: Calendar Logic Game

Name Any Weekday in 5 Seconds

Only for iPhone

Free · In-App Purchases · Designed for iPhone. Not verified for macOS.

iPhone

CAN YOU NAME THE WEEKDAY OF ANY DATE? OtterDay turns calendar calculation into a fast, satisfying logic game. Just as location-guessing games make geography feel playable, OtterDay does the same for dates. Learn a reliable mental method, practice it step by step, and work toward finding the weekday in five seconds—without checking a calendar. A SMART WORKOUT FOR YOUR BRAIN Every round challenges your logic, memory, number sense, and mental math. Short sessions keep your mind active while you build a practical skill that feels like a superpower: becoming a human calendar. LEARN, PRACTICE, MASTER Futuristic otter guides teach you the method one piece at a time. Start with recent dates, unlock wider ranges across centuries, and train until the calculation becomes second nature. WHY YOU'LL KEEP PLAYING • Guided lessons that explain the calendar method • Written and spoken-date challenges • Speed and precision training • Progress tracking and personal statistics • Achievements for accuracy, endurance, and fast answers • Flexible difficulty for quick practice or serious mastery MADE FOR CURIOUS MINDS OtterDay is designed for people who enjoy Sudoku, logic puzzles, mental math, number games, brain training, and learning clever systems. The method is related to John Conway's Doomsday Algorithm, presented as a focused puzzle adventure rather than a dry lesson. Keep your mind active. Sharpen your logic. Master the calendar—and see how close you can get to five seconds.

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This version includes several bug fixes.

Version 1.2.1

The developer, FELIX MANUEL PLAGGE, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Used to Track You

    The following data may be used to track you across apps and websites owned by other companies:

    • Usage Data

  • Data Linked to You

    The following data may be collected and linked to your identity:

    • Location
    • Usage Data
    • Diagnostics

Privacy practices may vary based, for example, on the features you use or your age. Learn More

Accessibility

The developer has not yet indicated which accessibility features this app supports. Learn More

Information

Provider
  • FELIX MANUEL PLAGGE
Size
  • 155.8 MB
Category
  • Puzzle
Compatibility
Requires iOS 15.6 or later.
  • iPhone
    Requires iOS 15.6 or later.
  • iPod touch
    Requires iOS 15.6 or later.
  • Mac
    Requires macOS 12.5 or later and a Mac with Apple M1 chip or later.
  • Apple Vision
    Requires visionOS 1.0 or later.
Languages
English and 4 more
  • English, French, German, Portuguese, Spanish
Age Rating
4+
In-App Purchases
Yes
  • Core To Pro ₪17.90
  • Core ₪19.90
  • Pro ₪24.90
  • Learn More
Copyright
  • © Felix Plagge Digital Labs
  • Developer Website
  • Privacy Policy

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