Want a ramp? Scribble a line. Want a box? Draw a rectangle. Want water? Grab the fluid brush. Everything you create instantly has mass, collision, and reaction to forces.

Today, Algodoo is used in classrooms from middle school to university. But it has never lost its original, joyful weirdness. Here’s what makes Algodoo different from every other physics simulator (including expensive ones like MATLAB/Simulink or even PhET):

At first glance, Algodoo looks like a toy—a colorful, 2D playground for bouncing balls and crashing cars. But after spending a decade away from it and coming back as an adult, I’ve realized something surprising:

That program was . Today, it lives on as Algodoo .