Why I Built PlayMemorize
My name is Christoffer De Geer, and I built PlayMemorize because I believe memory training should be free, fun, and accessible to everyone.
It started with a simple idea: I wanted a clean, distraction-free way to practice memorising the digits of pi. The apps I found were either cluttered with ads, locked behind paywalls, or just not enjoyable to use. So I built my own.
The core belief: memory training works best when the tool stays out of your way. No interruptions, no upsells, no timers pressuring you to buy. Just practice.
From One Game to Twenty-One
What began as a single pi digit trainer quickly grew. I realised that the same principles - spaced repetition, active recall, pattern recognition - could power many different kinds of learning tools. The goal was always the same: make learning easier in a minimalist, distraction-free way.
Every game on PlayMemorize uses one of three cognitive techniques. Spaced repetition for long-term retention (Pi Trainer, Polyglot). Active recall for rapid consolidation (Memory Game, Ghost). Pattern recognition for fluency (Color Memory, Speed Math). Pick the one that matches what you’re trying to learn.
Today PlayMemorize includes twenty-one free games, spanning memory, reasoning, and attention training:
- Labyrinth - Walk a fog-of-war maze and beat short challenges drawn from every other game, level by level
- Pi Trainer - Memorise thousands of digits of pi, e, the golden ratio, and 40+ mathematical constants
- Memory Game - Classic emoji card matching with adjustable grid sizes
- Geography - Learn countries, capitals, and flags on an interactive map
- Color Memory - A Simon Says-inspired color sequence game with up to 24 colors
- Ghost Memory - Spot the missing emoji from a memorised grid (Kim’s Game)
- Polyglot - Learn foreign vocabulary by matching words to emojis in 14 languages
- Speed Math - Sharpen mental arithmetic with configurable operations and ranges
- Unit Converter - Convert between metric and imperial units, or test your knowledge in game mode
- Crazy Comparisons - Pick the bigger number across wildly different scales
- Number Sequences - Find the next number in arithmetic, geometric, Fibonacci, prime, and power sequences
- Matrix Reasoning - Raven’s Progressive Matrices style pattern completion
- Odd One Out - Spot the item that does not belong across numbers, emojis, letters, shapes, and math
- Spatial Rotation - Find the rotated match among mirrored distractors
- Verbal Analogies - Complete word-pair analogies across function, location, part-whole, cause-effect, synonyms and antonyms
- Stroop Test - The classic color-word interference test that measures selective attention
- Facts - Spot the one true statement among several generated claims about math, calendar, and geography
- Define - Build vocabulary by picking the correct meaning of a word from multiple choices, in every one of the 25 languages
- Backwards - Read words in reverse and pick the forward-reading match from the options, with a millisecond-precision timer
- Illusions - Spot equal lengths, identical greys, and truly parallel lines across dozens of classic optical illusions
- Riddles - Solve classic, logic, math, and wordplay riddles across adjustable difficulty, type, and choice counts in streak mode
Design Principles
Every decision I made was guided by a few core beliefs.
No accounts, no tracking walls. You open the page and play. Your progress is saved locally in your browser - nothing leaves your device unless you choose to share it.
Works everywhere. PlayMemorize runs entirely in your browser - phone, tablet, or desktop. No app store downloads. It even works offline once loaded, so you can train on a plane, a train, or anywhere else the wifi drops.
Clean and calm. No flashing banner ads, no dark patterns, no countdown timers pressuring you to buy. Just a warm, muted design that lets you focus on the game.
Accessible by default. Touch targets meet WCAG guidelines. Keyboard navigation works. Screen readers can follow game state. Reduced motion is respected. These are not afterthoughts - they are the default.
The Technology
PlayMemorize is built with Astro and React, pre-rendered as static HTML for fast loading. Emoji rendering uses Twemoji SVGs so every player sees the same icons regardless of device. Sound is generated with the Web Audio API - no audio files to download. The whole site is open and free. No login, no subscription, no data collection beyond anonymous analytics.
Privacy note: PlayMemorize uses privacy-respecting analytics to measure page views and which games people play. No personal data is collected. If you want to opt out entirely, block analytics in your browser - the games will still work fine.
What’s Next
I keep adding games and improving existing ones based on what players tell me. If you have an idea for a new memory game or a way to make an existing one better, I’d love to hear from you.
Thank you for playing. Train your brain, have fun, and never stop learning.
- Christoffer De Geer
