Get started

Two ways in. The browser needs nothing at all, so start there; move to your own computer when you want to keep files and share what you made.

In the browser

Open the playground. It runs real Python — the same engine, the same code — with nothing to install and no account.

Paste this in and press Run:

from kaypy import *

kaypy(width=800, height=600, background=[141, 183, 255])

loadSprite("bean", "images/bean.png")
setGravity(2400)

add([rect(width(), 48), pos(0, height() - 48),
     area(), body(isStatic=True), color(90, 150, 70)])

player = add([sprite("bean"), pos(120, 100),
              area(), body(), anchor("bot")])


@onKeyDown("left")
def move_left():
    player.move(-320, 0)


@onKeyDown("right")
def move_right():
    player.move(320, 0)


@onKeyPress("space")
def jump():
    if player.isGrounded():
        player.jump(1000)

Arrow keys to move, space to jump.

There is no run() at the bottom and no loop to write. The frame loop starts by itself once your file has been read, which is why the first thing you write is the part you came for.

The first Run downloads Python itself and takes a few seconds. After that the browser has it cached and Run is immediate.

On your computer

kaypy needs Python 3.10 or newer. Installing it brings pygame-ce and nothing else:

pip install kaypy

Then make a game folder. This is not an empty one — it comes with a working game and the sprites it uses, so there is something to change rather than something to start:

kaypy new mygame
cd mygame
python game.py

A window opens with a character, some ground and a coin. Arrow keys to move, space to jump. Now open game.py and change a number.

kaypy new also fetches the lesson sound effects. If the network is blocked where you are it says so and carries on without them — the game still runs, it is just silent. When you want them:

kaypy sounds mygame

Put it on the web

One command turns a game into one HTML file:

kaypy web game.py

That writes web_build/game.html — about 260 KB for the starter, with the sprites carried inside it. Double-click it to play, or upload that single file to itch.io as an HTML project. Nothing else has to go with it.

The first time somebody opens the page it downloads Python, the same as the playground does. After that it is cached.

Where to go next

• Learn Python — conditionals, loops and lists, from the beginning, for somebody who has not programmed before.
• Guide — thirteen lessons that build on the starter game: sprites, collision, gravity, scenes, sound, levels, camera, state.
• API — every name in kaypy, with a runnable example each.
• Games — things people have made, and how to send in yours.

If something goes wrong

kaypy: command not found — the install worked but the script is not on your PATH. The module does the same thing:

python -m kaypy.cli new mygame

The window opens and closes at once — that is usually an error printed and gone. Run it from a terminal rather than double-clicking, and the traceback stays on screen.

GameObj has no attribute ... — an object is missing the component that provides it. player.jump() needs body(); player.onCollide() needs area(). The Guide has a section on this, because it is the error everybody meets first.