What got me into programming was my father writing an engine simulator in BASIC. Albeit for different reasons: he was a mechanical engineer and wanted to compare the torque curves of various engine designs. He used CIRCLE and LINE statements to draw an animated (<1 fps) wireframe of the piston, crank assembly, and crankshaft in operation (though he only completed one engine type this way), and that was the real holy-crap moment for me: that you could use this machine to draw things and make them move.

The fact that this guy did the same thing, just to have better sounding racecars in his vidya, blows my mind.