The Learning Guide

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CEMI Fútbol is built on one idea: learning is seasoning, never the meal. A "Nerd Engine" sprinkles real facts as flavor after a shot, a save, or an elimination — it never blocks the game. Your job as the educator is simply to notice those moments out loud.

Why it works in class or at home

• Ages 8–16. The controls are one-finger simple; the ideas underneath scale from primary curiosity to secondary physics.
• No install, no barriers. Runs in any modern browser — Chrome, Firefox, Safari, Edge. No plugins, no downloads.
• Free and offline-capable. Once the page has loaded it keeps working without a connection, so it is fine for spotty Wi-Fi labs.
• Kid-safe. No account, name, or email is ever required to play. An optional profile is stored only in the browser.
• Four languages. English, Español, Français, Português — switchable at any time, which is itself a teaching tool (see Languages below).

Before, during & after play

You do not need to be a gamer to run these. Three light-touch habits turn play into learning.

Before

• Play one round yourself. Five minutes is enough to know how a swipe becomes a shot, and how the gorilla telegraphs its charge.
• Pick one subject lens. Decide today is a "physics day" or a "biology day" and choose one or two activities below — don't try to cover everything at once.
• Set the language. For a languages lesson, agree on which language the group will play in, or plan to switch mid-session.

During

• Read the facts out loud. When the Nerd Engine pops a line after a shot or an elimination, pause and ask "wait — is that true?" Curiosity beats correctness.
• Ask for a number. Golden Boot reports your shot's speed in km/h and its energy in joules. Have students say the numbers before the next shot.
• Encourage a log. A phone or a scrap of paper is enough. Several activities below are just structured observation logs.

After

• Round-robin reflection. Most surprising fact, hardest moment, best goal. Thirty seconds each.
• Verify one claim. Send students to check a single fact from the game against another source. Was the game right?
• Extend into the code. For older or curious students, the Programming guide turns the same games into a reading-real-code lesson.

Privacy & safety: two ways to play

CEMI Fútbol is designed for classrooms, so the safest option is also the default one. The account panel offers two clearly separated ways to play — and nobody is ever required to choose either one just to play.

Local mode — the default, made for kids

• A nickname is all there is. No email, no password, no real name, no birthday. Even the nickname is optional.
• Everything stays on the device. Nickname, records and achievements live only in that browser. Nothing is ever sent to any server — not quietly, not "anonymized", not at all.
• Clearing the browser erases it. That is the promise of the mode, not a flaw: the data lives nowhere else.
• An honest erase button. The panel includes an "erase my local data" button that wipes the profile and every local record on the spot (it asks for a second tap to confirm). Useful between class groups on shared computers.
• A look-only window on the world. One optional toggle lets a local player view the world leaderboards. It is strictly read-only: their own scores still never leave the device.

Cloud mode — optional, for players who want to compete

• Sign in with Google or with an email and password. The player (or their family) chooses to switch; it never happens on its own.
• Progress syncs across devices. Signing in merges what is on the device with what is in the cloud, keeping the best of both — progress is never lost by switching computers.
• Leaderboards. Best scores appear on the global leaderboards under the chosen nickname.
• Reversible. Signing out returns the player to local mode at any time.

Nickname safety

Every nickname a player types is checked automatically against offensive, discriminatory, sexual and abusive words in all four of the game's languages. The check is not naive: it also catches the usual disguises — dots or underscores between letters, extra spacing, repeated letters, and swapping numbers for letters ("leetspeak"). A rejected name simply asks the player to pick another one. And the leaderboards double-check every name before showing it, with the server correcting anything that slips through — so an inappropriate name never appears on a classroom screen. If one is ever detected, it is quietly replaced by a harmless football nickname such as "Golazo#417".

Physics of the perfect shot

Golden Boot solves real ballistics for every shot. Swipe speed becomes launch speed, the swipe's end point becomes the aim on the goal plane, and a curved swipe adds spin. After the ball crosses the line, the Nerd Engine reports the actual numbers — km/h, joules, milliseconds, degrees — from games/golden-boot/shootout.js.

Gorilla biology & behavior

The gorilla in this game is not a cartoon. It knuckle-walks with real diagonal limb pairs, beats its chest as an honest warning before it charges, hunts the most isolated player like a real predator, and runs on stamina it must recover. Its behavior is a living observation subject.

Four languages, one game

Everything in both games is translated into English, Español, Français and Português, switchable any time. Because the same action produces the same word in every language, the game becomes a natural vocabulary machine.

Math & Geography

The 32-nation tournament is a powers-of-two machine, the flags open a world map, and the leaderboards are a statistics dataset waiting to happen.

Programming — the code is open

Both games are zero-build, readable JavaScript with learning-oriented comments. The whole engine is meant to double as a programming lesson. These three activities are a taste; the full Programming guide has a file-by-file map and a live source viewer.

The simplest physics in the whole catalog

A ball falls, you tap to kick it back up, and that is the entire simulation — gravity pulls it down, your tap sets a new upward speed. Keepy-Uppy Infinito is the best first stop for a student who has never read game code before, because its physics loop in games/keepy/main.js is only three lines long.

A predator that grows every time it eats

The anaconda in games/anaconda/main.js is a chain of points, each one following the point ahead of it at a fixed distance — the classic "Snake" body, reused as a predator. Every time it swallows the ball it pushes new points onto its own tail, growing in real time in front of you.

Eight power-ups, one small system

Rumble Fútbol seats up to four players (people or bots) around one screen and drops random power-ups onto the pitch. games/rumble/main.js is a tidy example of how professional games avoid writing eight separate features for eight different effects.

When the field itself plays

Water, earth, air and fire each get a character AND a home arena in games/elemental/main.js — and the arena is not just scenery. Step into a lava pool and the ball speeds up; the wind in the air arena keeps shifting. The pitch is a second opponent.

Decide the traffic once, draw it forever

Cruce de Tráfico hops your player and ball across eight lanes of streets, rivers and train tracks. games/cruce/main.js is a clean example of separating "roll the dice" from "compute the picture right now."

A horde is one object, copied many times

In Muerto FC a lone striker scores while a horde of slow zombies grows larger after every goal. games/muerto/main.js shows how a scary difficulty ramp can be nothing more than the same object pushed into an array again and again.

You can see exactly where it will land

In Dodgeball FC, three rivals throw dodgeballs whose landing spot is decided the instant they leave the hand — games/dodgeball/main.js turns a real physics fact (a thrown ball's landing point is fixed the moment it launches) into a fairness mechanic you can literally see coming.

The words the gods left behind

Zeus, Hermes, Poseidon and Hades are more than character names in games/gods/main.js — every one of them left a word behind in modern English, Español, Français and Português. This game is a doorway into etymology: the study of where words come from.

An explosion is just a distance check

In FIREBALL FC nobody ever touches the ball — two wizards cast fireballs and use the blast to shove it toward the goal. games/fireball/main.js turns a blast radius into a few lines of readable math, plus a mana bar that forces players to budget their spells.

A whole game, scripted before the first pitch

A robot pitches, you swipe to kick — Béisbol Gol's games/beisbol/main.js pre-plans every one of its 54 pitches before the first one is even thrown, and fakes convincing curveballs with nothing but sine waves.

Hunting where the ball will be

Water behaves differently from grass, and games/dolphins/main.js knows it: every swimmer — your pod and the sharks alike — shares one momentum function, and the hunting shark aims not at the ball, but at where the ball is about to be.

Ten floors, one small table

Dungeon Striker sends you down ten themed floors, each a 45-second match against a different goalkeeper. games/dungeon/main.js shows the biggest procedural-generation and seeded-RNG lesson in the whole catalog — an entire ten-floor run is decided before you take your first step.

Three separate dice, so nothing steals from anything else

Endless Striker swerves you down a three-lane dribble run in games/striker/main.js. It is also the game that sets up the catalog's most advanced lesson: sometimes one shared game needs several completely independent seeded random-number generators.

The same game, a different set of paints

This is the catalog's flagship lesson. Endless Striker 3D is not a new game — its own header comment in games/striker3d/main.js says so directly: the same rules, the same numbers, the same daily seed as Endless Striker, rebuilt with a real 3D camera instead of a flat canvas.