# Doomsday Method \| Mental Game — Master an Extraordinary Skill > App to learn and practice calculating the weekday of any date. (iPhone/iPad app by Leon Grimmeisen.) - Source: https://appshunter.io/ios/app/doomsday-method-mental-game/id6447447000 (this page in markdown: same URL + `.md`) - Developer: [Leon Grimmeisen](https://appshunter.io/developer/1654025400) - Category: Education, Games, Casual, Trivia - Price: Free - Rating: 4.50/5 from 2 App Store ratings · 2 written reviews indexed - Age rating: 4+ - Requires: iOS 17.0 · 10 MB - Languages: American English - Released: 2023-06-12 - Data updated: 2026-08-24 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/doomsday-method-mental-game/id6447447000/reviews.md ## What is Doomsday Method | Mental Game? Someone tells you the date they were born. You tell them it was a Monday. That is a real skill, it takes about a week to learn, and this app teaches it end to end. The Doomsday algorithm — invented by the mathematician John Conway — turns any date into its weekday using arithmetic small enough to finish while someone is still saying the date. No lookup. No phone. No calendar. LEARN 48 lessons across 11 chapters, in three parts 178 checkpoint questions. You answer in your head, then check yourself against the worked reasoning — nothing is graded, and nothing is rushed Interactive calendars, anchor tables and step-by-step walkthroughs inside the lessons themselves Mnemonics that stick: 4/4, 6/6, 8/8, 10/10, 12/12, and "9-to-5 at the 7-Eleven" Six different ways to work the year offset. Pick the one your head likes, and every worked explanation in the app is rewritten in it Seven Extras: why the method works, Easter and the computus, the Julian calendar, Conway's own shortcuts, the record holders, and full reference tables A cheatsheet with every anchor and every offset on one screen TRAIN 10 drills: weekday numbers, counting in sevens, leap years, century anchors, the year offset, month doomsdays, day counting, reverse dates, Julian dates and Easter Five stars a drill, earned by answering cleanly — right, and inside that drill's target time Nothing cuts you off mid-question, and training never costs you rating PLAY Classic — endless real dates, at your own pace, with no clock at all Daily Challenge — five dates drawn from the day itself, identical for every player on earth, one attempt a day Time Attack — two minutes, as many dates as you can, ten seconds off for every miss Choose your range: 2000–2099, 1800–2199, or the whole Gregorian calendar from 1583 to 2599 YOUR PROGRESS A Doomsday Rating that rises when you are right and quick, and never pays for a guess Accuracy and speed over time, your rating history, and a 12-week activity calendar Game Center leaderboards for today's challenge and the global rating, friends included BUILT PROPERLY No account, no sign-up, no ads Works offline Every number in every lesson is re-derived by a checker that shares no code with the app, so an explanation cannot drift from the answer it gives Analytics are opt-in, pseudonymous and on EU servers. You are asked once, and can change your mind any time in Settings Coming from the old Doomsday Method? Your history is imported and replayed answer by answer, so your chart reaches back and your rating arrives honest Start free. One optional purchase opens the rest — one payment, not a subscription. --- EULA: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ ## Key features - Learn Doomsday Method principles - Interactive examples and tips - Dedicated training mode - Progress tracking and statistics - User-friendly interface ## Recent user reviews (2 of 2) All indexed reviews: https://appshunter.io/ios/app/doomsday-method-mental-game/id6447447000/reviews.md ### 4/5 — Overall good! *2026-05-19* A good trainer. Some dates you get correct, but the statement below says a different day of the week. Small bug I’m sure is an easy fix. Would love an Apple Watch version too!!! **Developer response:** Thanks for the review and for catching that! You're right, there was a bug affecting some date calculations. Great news: I just released an update that fixes this issue. Give it a try and let me know if everything checks out now. If you're happy with the fix, I'd really appreciate it if you considered updating your rating, it helps a lot as a small indie app! 🙏 ### 5/5 — Overall great! *2026-04-29* Updated review - works great 5 stars! Would love an Apple Watch version too!!! **Developer response:** Thanks for the review and for catching that! You're right, there was a bug affecting some date calculations. Great news: I just released an update that fixes this issue. Give it a try and let me know if everything checks out now. If you're happy with the fix, I'd really appreciate it if you considered updating your rating, it helps a lot as a small indie app! 🙏 ## Frequently asked questions about Doomsday Method | Mental Game ### What is the Doomsday Method app? The Doomsday Method app teaches you John Horton Conway's technique for calculating the weekday of any given date. It offers learning resources, practice modes, and progress tracking to help you master this skill. ### How does the Doomsday Method app work? The app guides you through understanding the Doomsday Method's principles with engaging slides and interactive examples. You can then practice calculations in the training mode and monitor your improvement. ### Is the Doomsday Method app suitable for beginners? Yes, the app is designed for curious learners and provides a user-friendly interface to make mastering the weekday calculation technique accessible to everyone. ### Can I track my progress in the Doomsday Method app? Absolutely. The app features detailed statistics to track your performance, highlighting areas of strength and suggesting areas for further practice, helping you see your skills improve over time. ### What devices does the Doomsday Method app support? Currently, the Doomsday Method app is supported on iPhone devices. ### How often is the Doomsday Method app updated? The latest version is 1.1, and the app was last updated on April 28, 2026. This indicates a recent update, suggesting ongoing development and support. ### Does the Doomsday Method app have ads? No, the Doomsday Method app is ad-free, providing an uninterrupted learning experience. ### What is the age rating for the Doomsday Method app? The Doomsday Method app has an age rating of 4+, making it suitable for a wide range of users interested in learning. ## Version history (last 4 releases) ### 2.0 — 2026-08-19 Doomsday 2.0 is a complete rewrite. Everything below is new. A REAL COURSE 48 lessons across 11 chapters, with 178 checkpoint questions, interactive calendars inside the lessons, and seven Extras — why the method works, Easter and the computus, the Julian calendar, Conway's own shortcuts, and the people who hold the records. Plus a cheatsheet with every anchor and every offset on one screen. TRAINING THAT DIAGNOSES 10 drills — one for each step of the method, the three fundamentals underneath it, and the three it opens up: reverse dates, Julian dates and Easter. Five stars each, earned by answering cleanly rather than merely correctly, so the bar tells you which step is actually slowing you down. And no drill cuts a question off any more. THREE WAYS TO PLAY Classic is endless and now has no clock at all. The Daily Challenge gives every player on earth the same five dates. Time Attack is two minutes, with ten seconds off for every miss. A RATING THAT MAKES SENSE One Doomsday Rating, explained in four lines: right and quick is worth most, wrong is worth nothing, and no single answer can move it by more than a fixed amount. Alongside it, accuracy and speed trends, rating history and a 12-week activity calendar. SIX METHODS, YOUR CHOICE Choose how you work the year offset, and every worked explanation in the app is rewritten in your method. COMING FROM VERSION 1 Your old history is imported and replayed answer by answer through the new rating, so your chart reaches back into version 1 and your rating arrives honest rather than reset. Also new: no account, no ads, works offline, and analytics that are opt-in and stay on EU servers. ### 1.1 — 2026-04-28 bug fixes ### 1.0.1 — 2024-05-21 - updated website links ### 1.0 — 2023-06-12 No release notes. ## Apps similar to Doomsday Method | Mental Game | App | Rating | Price | Category | | --- | --- | --- | --- | | [Day of Week Pro](https://appshunter.io/ios/app/day-of-week-pro/id1662589371) | 4.0 (3) | Free | Education | | [Morse Mania: Learn Morse Code](https://appshunter.io/ios/app/morse-mania-learn-morse-code/id1511042196) | 4.9 (8,040) | Free | Education | | [LingQ \| Learn Languages](https://appshunter.io/ios/app/lingq-learn-languages/id379385811) | 4.7 (10,097) | Free | Education | | [memoryOS: Memory Games](https://appshunter.io/ios/app/memoryos-memory-games/id1553283646) | 4.9 (15,048) | Free | Education | | [Doomsday calculator memory](https://appshunter.io/ios/app/doomsday-calculator-memory/id6503307628) | 5.0 (1) | Free | Education | | [WeekdayWidget](https://appshunter.io/ios/app/weekdaywidget/id6745067970) | 5.0 (10) | Free | Education | ## More apps by Leon Grimmeisen - [WorkoutPulse \| Tabata Timer](https://appshunter.io/ios/app/workoutpulse-tabata-timer/id6444348524) - [Health Pulse](https://appshunter.io/ios/app/health-pulse/id6497484745) - [Tick - Habit & Task Tracker](https://appshunter.io/ios/app/tick-habit-and-task-tracker/id6757186751) - [Busfahrer Partyspiel](https://appshunter.io/ios/app/busfahrer-partyspiel/id6758355578) - [Leben in Deutschland Pro](https://appshunter.io/ios/app/leben-in-deutschland-pro/id6759523195) All apps by Leon Grimmeisen: https://appshunter.io/developer/1654025400 ## Related topics [doomsday method](https://appshunter.io/ios/topics/doomsday-method) · [leon grimmeisen](https://appshunter.io/ios/topics/leon-grimmeisen) --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-24.*