A perforated chassis, a box of parts, and a robot that has to roll. You bolt the mechanics underneath, you wire the electrics on top, you switch it on — and then you find out what you got wrong.

Build with real parts

Solenoids, gears from 8 to 32 teeth, connecting rods, crank pins, bearings, shafts, drive wheels, flywheels, a contact breaker, capacitors, a resistor, a switch. Every part has a data sheet, real dimensions and a place where it fits. Nothing snaps magically into position: if your two shafts sit a few millimetres too far apart, the gears will not mesh, and the game will tell you by how much.

Nothing is faked

Ten thousand times a second, the game solves a real system of equations to find the voltage at every point of your build and the current in every wire. That is why your machine behaves like a machine. It stalls at dead centre until you fit a flywheel. Your breaker contacts erode spark by spark until they stop conducting — and a capacitor in the right place will save them. The connecting rod tears off if you stretch the linkage too far.

Every failure has a cause, and you can find it

Press F1 and the Encyclopaedia opens: every part, every idea, every fault, cross-referenced. Not a manual — a workshop notebook that explains why the spark eats your contacts, and what a magnetic field has to do with any of it.

In this demo

Eleven build missions, from a solenoid you slide in and out by hand to a robot that drives itself down a track on its own battery. Then a free sandbox, with the parts box open.