Fractals, simulations, physics, games and demos — all written in BASIC-256. Read the source of any of them, or run it in your browser with one click and change it yourself.
Infinite detail from a few lines of arithmetic.
Kurt Moerman, adapted by UglyMike
A Julia set redrawn live as you move the mouse over the canvas: the pointer picks the constant, so every position is a different fractal.
JuliaMoerman.kbs
After Simone Conradi
Clifford and Peter de Jong attractors. Move the mouse slowly to explore the parameter space; points visited more often glow brighter through additive blending. Click to clear the trails.
StrangeAttractors.kbs
After Paul Bourke
Several Julia sets combined into one iterated function system, rendered by counting how often each pixel is hit. Heavily commented, so it doubles as a walkthrough of the technique.
MultiJuliaIFS.kbs
Simple rules, many agents, surprising behaviour.
UglyMike
Particle Life: coloured particles attract or repel each other by a handful of simple rules, and cells, chains and swarms emerge. Press R for a new set of rules.
particle_life_final.kbs
A Physarum-style slime mold simulation. Sliders change sensor distance, sensor angle, turning angle and step size while it runs, so you can watch the network reorganise.
SlimeMoldSimulation_GUI.kbs
A cloudy sky painted row by row from six layers of OpenSimplex noise, coloured with HSV. Four numbers at the top of the program set how cloudy it is, how soft the edges are, how big the clouds are and how much fine detail they have.
CloudySky.kbs
Verlet integration: position, previous position, and nothing else.
Balls of different mass under gravity and friction, colliding according to their weight. Grab one with the mouse to shove the others aside. A uniform spatial grid keeps the collision checks fast.
verlet balls part 5_Optim.kbs
A chain of Verlet particles joined by fixed-length sticks, pinned at one end. Drag the pinned end with the mouse and the rope swings, bounces off the walls, collides with itself and wraps around two fixed discs.
verlet rope part 5_collision.kbs
A sheet of cloth built from a grid of Verlet points and constraints.
K Moerman
Two linked pendulums swinging under gravity with a little drag, worked out step by step from the equations of motion, while the lower weight traces its chaotic path. Any key stops it.
DoublePendulum.kbs
UglyMike
A particle smoke simulator from the Nature of Code series. Move the mouse left or right to change the wind.
Smokesimulator.kbs
Complete, playable games written in BASIC-256.
Flood the whole board with one colour, starting from the top-left corner, in as few moves as you can.
Flood-It.kbs
Manuel Nogueira Santos
A minimalist Flappy Bird: click to flap through five levels of obstacles, with mountain backdrops, before your lives run out.
FlappyBall2.kbs
Written entirely by Claude AI
Snake on a synthwave circuit board. Crash and the snake detonates into a neon particle system. Arrow keys or WASD to steer; needs a keyboard.
ClaudeAI-neonsnake.kbs
Buttons, sliders and menus, drawn from scratch on the graphics canvas.
A tour of the BTK2 GUI toolkit: buttons, checkboxes, radio buttons, sliders and spinners, each one built from BASIC-256 drawing commands.
BTK2_Toolkit_demo.kbs
A Mandelbrot explorer with its own interface: drag out an area to zoom, set the iteration count, and hover over any point to preview its Julia set — click to render it in full.
Mandelbrot-256.kbs
UglyMike
A complete paint program: pencil, pen, spray can, fill, shapes, lines, Bézier curves, a colour picker and custom colours, with undo and save.
BasicPaint.kbs
A particle fountain that follows the mouse pointer, with up to five thousand particles in flight.
ParticleFun.kbs
Eye candy, in the demoscene tradition.
Paul Dunn; ported by Toby Nelson and UglyMike
Paul Dunn’s famous SpecBAS demo, plus variations on it, selected from the keyboard.
BubbleUniverse_variations.kbs
K Moerman, from a sketch by yuruyurau
A creature drawn from thousands of short lines, rippling as it swims. BASIC-256 is interpreted, so you watch it swim in slow motion.
Quiverbloom.kbs
The classic warp-speed starfield: three hundred stars streaming out from the centre of the screen.
Warpfactor_Starfield.kbs
Ported from John Penner’s QB64 code
Rotating, colour-cycling field lines with a touch of transparency.
FieldLines.kbs
Two balls fight for territory: each one repaints the squares it hits in its own colour, and the score is how much of the board it owns.
PongWars2.kbs
Programs that live in the text window.
Bobby Breitling’s C64 one-liner
A Commodore 64 one-liner reborn on the 2.3.0 text screen: green balls push up from the bottom, blue ones rain down from the top, and the two fight over a 40×25 character grid.
GreenVsBlue.kbs
A starting point for a menu-driven text program: a coloured banner, a numbered menu and a prompt, all placed with LOCATE on a TEXTSCREEN grid. Fill in the four options with something useful.
FormTemplate.kbs
"Run in browser" opens the program from run.basic256.org in a separate window and runs it on its own, without the editor — the first visit downloads roughly 16 MB, and a few programs need a mouse or keyboard. Programs with a run button also ship in the Examples folder of the desktop app; the others link to their source on UglyMike's Web Lair.
Open any of these, change a number, and run it again — that is how most of them started.