FlagStack teaches over 200 flags in the app, gives every one of them a written story about where its design came from, and uses a spaced repetition schedule to decide when you should see that flag again, inspired from researched and effective learning methods. It also lets you play what you have learned across seven modes.

Free. No ads anywhere near a question. Works offline.

WHY EACH FLAG LOOKS THE WAY IT DOES
Most flag apps test recognition and stop there. FlagStack writes a real story for every flag, in chapters, about the people and the arguments and the accidents behind the design. Tap any part of a flag to read what that crescent or star or stripe is doing there. Knowing why gives your memory something to hook onto.

A SCHEDULE THAT KNOWS WHICH FLAG TRIPS YOU UP
Every answer you give feeds a review schedule. Flags you get right come back later, flags you miss come back sooner, and the app builds each session for you rather than making you pick. Reviews stop at 25 cards a day. That cap is not a paywall and not an energy meter. Spacing is what makes the next review stick, and cramming fades inside a week.

THE FLAG CHALLENGE
Two tracks across 196 flags. Sprint covers the set in 21 days at roughly 14 flags a day. Habit spreads the same material over 66 days at 4 or 5. On either track exactly one lesson unlocks per calendar day, so it cannot be rushed, and both end in an exam over everything you were taught.

SEVEN WAYS TO PLAY
Flag Reveal. Six tiles hide a flag and every wrong guess uncovers one, with each miss telling you how far off you were and in which direction.
Tap the Map. A country's name appears and you find it on a map you pan and pinch yourself. Nothing to eliminate.
Daily Challenge. At midnight UTC the whole planet gets the same questions. Ten seconds each, one attempt, then it is gone until tomorrow.
Real-time battles. You and a rival answer the same questions at the same moment, side by side. If nobody is around, GeoBot adapts to your rating.
Classic quizzes. Flags, capitals or everything mixed. Pick a region and a length, then turn on typed answers for when multiple choice feels soft.
Quick Study. Flash cards, for a spare minute.
Your Kind of Place. Thirteen sliders scored against every country, to find where you would actually fit.

201 FLAGS, DRAWN PROPERLY
Every flag at its true proportions, Nepal's pennants included. Look-alikes are taught next to each other, so Chad and Romania, or Indonesia and Monaco, encode as a difference instead of two blurs.

OFFLINE BY DESIGN
Every flag, story and map ships inside the app, and your phone builds the quizzes itself instead of asking a server for them. Even the country matching runs on the device. FlagStack reaches for a connection only when something genuinely needs one, which means battles, leaderboards, and backing up your progress.

NO SIGN-UP FORM
FlagStack makes an account for you the first time you open it, with a random username and an avatar, and asks for no email address and no password. Everything works from that first minute, leaderboards and battles and your streak included. Adding an email later under Save Your Progress is what carries your progress to a new phone.

ALSO IN THE BOX
A weekly top-100 leaderboard. Achievements that arrive one at a time. A 30-day streak calendar. Follows and friends. Share cards for every mode. Reporting and blocking anywhere someone can post. A certificate waiting at the end of the challenge.

Every mode and every flag is free.