Building Flag Guesser with Claude

Meet Flag Guesser

Flag Guesser is a free guess the flag game you play in your browser. You see a flag and pick its name. That’s the core, but around it there are routes, hearts, timers, stamps and a passport full of visas to collect. No sign-up, no ads, no backend. Your progress simply lives in your browser.

I built it with Claude Code over about two days. The first commit landed on 17 October 2026, and it took about 30 commits. This post covers why I made it, how it plays, and how it was designed.

Why I Built It

I like creating games, and I play this kind of game online. But the flag quizzes I’ve played all have the same feeling: a flag, a multiple-choice question, next. Very few features and very little gamification.

I also like playing GeoGuessr, and I wanted my flag quiz to feel like an actual game, something with progression, a bit of pressure and a reason to come back. So Flag Guesser is for people like me: anyone who enjoys geography games and wants more than “flag + MCQ”.

How It Plays

There are 225 flags split into 15 levels of 15, ordered from the most recognisable to the least, plus a 10-flag bonus level. Every flag keeps its true official proportions.

The same flags can be played on three routes. Each one tests a different skill. All routes are open from the start, and the levels inside a route unlock one by one.

✈️ Tourist: can you recognise it?

• 4 options, and the flag stays visible the whole time
• No hearts, so you can’t fail out of a level
• ★★★ means 15/15 within 60 seconds

🚆 Explorer: can you tell the neighbours apart?

• 4 options, all from the same region as the answer
• 3 hearts, and the flag hides after 5 seconds
• ★★★ within 75 seconds

🚢 Diplomat: can you remember it?

• Memory mode: the flag shows alone for 3 seconds (or until you tap “Got it”)
• Then it hides and 6 look-alike options appear
• 3 hearts, and no side-by-side comparison after a miss
• ★★★ within 105 seconds

The wrong options are not random. Each country has curated look-alike flags and names (think Chad and Romania, or Indonesia and Monaco), so the harder the route, the trickier the options.

The whole game uses a passport theme. Levels are stops on a route map, a cleared level gets a stamp, and every flag you get right becomes a visa in your collection. There’s also a day streak, a 3-2-1 countdown, original synthesised sound effects, dark and light themes, a reduced-motion option, and a spinning neon globe on the home page.

Designing It

It started as a written plan, not code: the rules, the screens, the order of the flags and what was out of scope. Claude Code wrote the code from that plan, and the game runs as static files on AWS. That’s the whole technical story.

From quiz to game

The first playable version worked, but it looked like every other flag quiz, which is exactly what I set out to avoid. The new direction was dark, glassmorphism and glowing cards with micro-animations, inspired by a couple of Dribbble shots. The navbar went, because it broke the game feel, and the flag’s glow now takes the flag’s own colours.

Plenty didn’t survive: a twilight background, a sharp-edged sci-fi card style and a realistic globe that lost to the neon one. When trying an idea takes minutes, throwing it away costs nothing.

Playtesting decides

Playing it, I couldn’t feel any real difference between the three routes. On paper they were different, but in my hands they felt the same. So each route got its own rules and its own identity: hearts, a flag that hides, and finally a memory mode where the options only appear after the flag is gone. That last idea came after the game was already live.

Looking back

I wouldn’t do it differently. The creative ideas came along the way, not in advance. The memory mode, the routes and many of the UI decisions only appeared once I could play the previous version. I’m proud of every new version.

But if I’m being honest, I still have an inner thought that I personally don’t like the UI. So that’s still on my list.