Roderic Andrews — Case Study Roderic Andrews rodericandrews.com ↗
Case Study · Real estate

Guessimmo.

guess the price of Paris real estate

A free, addictive game that teaches you to value a property like a pro. Real Paris listings, real sale prices pulled from DVF open data — AI-generated visuals over a real price engine. Twenty arrondissements, one question: tu tiens combien?

Read the brief
01 · The BriefGM·CS

What it is, and the call that made it.

What it is guess the price of Paris real estate

A free, addictive game that teaches you to value a property like a pro. Real Paris listings, real sale prices pulled from DVF open data — AI-generated visuals over a real price engine. Twenty arrondissements, one question: tu tiens combien?

the unobvious call Guessimmo in one move.

DVF publishes every real Paris sale; nobody had made it playable. I built the price engine first, then wrapped it in a guessing game so the feedback loop teaches valuation instead of merely reporting it. Concept, design and build were mine.

02 · The Work3 views

Seven phases. One number.

A round is not one guess. It is seven phases — price, defects, strengths, energy rating, fees, era, then the reveal — and each one moves the number you are committing to. That is the design: valuation is not a single judgement, it is an accumulation of them.

The feed is deliberately social. Listings scroll like a vertical video feed, with likes and a running bankroll, because the format people already scroll is the format that teaches without feeling like homework.

Every price is real. DVF publishes every recorded sale in France; the game is a wrapper that turns that public record into a feedback loop.

Guessimmo landing page — Tu sais guesser les prix de Paris ? / Guessimmo guess screen — a Wagram apartment with two candidate sale prices (1 of 2)
Guessimmo landing page — Tu sais guesser les prix de Paris ? / Guessimmo guess screen — a Wagram apartment with two candidate sale prices (2 of 2)
Landing + Phase 1GM·CS·01
GM·CS·01

The Front Door & The Guess

One question, asked in the local idiom.

The whole proposition in a single screen: real DVF sale prices, twenty arrondissements, free. The three proof points sit under the CTA rather than above it — the question earns the click first. The listing carries exactly what a valuer would work from — arrondissement, type, surface, floor, lift, balcony, view — plus the neighbourhood median per square metre. Then two candidate prices, and no way to move on without picking one.

Use case A player arrives from a share link and starts in one tap.

No account, no onboarding, no tutorial. The headline states the game, the button starts it, and the legal note about AI-generated visuals sits where it belongs — visible, not hidden.

Guessimmo higher-or-lower round with a 2.3x speed multiplier and countdown bar / Guessimmo hidden-costs phase — ten markers allocated across five cost columns (1 of 2)
Guessimmo higher-or-lower round with a 2.3x speed multiplier and countdown bar / Guessimmo hidden-costs phase — ten markers allocated across five cost columns (2 of 2)
Higher or lower + Phase 5GM·CS·02
GM·CS·02

Higher Or Lower & The Hidden Costs

Hesitate and it costs you.

A second mechanic on the same listing: a price is shown, and the only question is whether the real one sat above or below it. A countdown bar runs and a speed multiplier climbs, so answering fast is worth more than answering safe. Ten markers, five columns — notary, agency, works, vendor file, energy survey — and the instruction that ten markers equal one hundred per cent of the hidden cost. The more a line really costs, the more it deserves.

Use case A 182 m² T5 on Monceau, shown at 1 950 000 €.

The multiplier reached 2.3× before the call was made. Speed is scored because a professional valuer does not deliberate for a minute on a property they know — fluency is the point, not arithmetic.

Guessimmo scorecard — real sale price, precision, gap, grade and an itemised cost breakdown
Phase 7 · the reveal and the receiptGM·CS·03
GM·CS·03

The Reveal

Marked, then explained.

The real sale price, the precision percentage, the gap and a letter grade — then the receipt underneath: final price against real net-to-vendor, bonus, bankroll, and every hidden cost itemised down to the diagnostics line.

Use case 55% precision. 467 850 € under. Grade D.

A wrong answer is more instructive than a right one here, because the breakdown shows exactly which assumption was wrong. That is the feedback loop the price engine exists to serve — the game is the interface to it.

03 · The Delivery40 days

Built and shipped.

40 days DURATION
379 commits EFFORT

Sector: Real estate · Role: Concept · Design · Build · Data: DVF open sale prices

Designed, engineered & shipped by Roderic Andrews — Product Designer & Design Engineer

04 · The Pitchhire the operator

Hire the operator.

Guessimmo is the evidence. Your product is the point.

Everything on this page — the engineering, the design, the positioning — was built by one operator. That's the offer: a product designer who writes the code and wires the growth. No hand-offs, no telephone game, no agency margin.

Design · Engineering · Marketing · Intelligence · Video · Growth

Book the walkthrough.

Thirty minutes. The build, end to end.

I'll walk you through how it was built — live, with your questions.