Around 1855 James Clerk Maxwell spun discs painted in coloured sectors to measure colour itself. Below a few turns per second the eye tracks each sector; above the flicker-fusion threshold the retina can no longer resolve the flashes and simply averages the light arriving over time.
That average is additive — a mean of the light, the way coloured lamps add — not the subtractive mix you get by stirring the wet paints together, where each pigment subtracts more of the spectrum and the result turns muddy. Red-orange beside its cyan-blue complement spins to a neutral grey; the same two paints stirred give brown.
This is exactly the trick of the Pointillists. Seurat and Signac set dots of pure pigment side by side and let the eye do the mixing at a distance — optical, additive mixing — so their canvases hold a luminosity that pre-mixed paint can never reach.
The simulation stopped unexpectedly — the lesson continues without it. You can move on; nothing you did was wrong.