1. Open a window
Click or tap close to the middle wall. That part opens (it glows green) for about half a second. Drag along the wall to open more.
Sort a jiggling gas: get the red balls to the left side and the blue balls to the right side — only by opening tiny windows in the middle wall.
Click or tap close to the middle wall. That part opens (it glows green) for about half a second. Drag along the wall to open more.
Open a window just as a red ball is about to go left, or a blue ball is about to go right. Keep it shut for the others.
It shows how many balls are on their correct side. 50% means fully mixed; 100% means perfectly sorted.
Reach %: a stopwatch runs until you stay above the Target for 1 second. 60s Best %: you have 60 seconds, and your highest score counts.
Sliders set speed, number and size of balls, noise, wall slices, window size and Latch (how long a window stays open). Reset mixes a new gas.
In the 1860s Maxwell imagined a tiny “demon” that sorts a gas just by opening a door — you are the demon! It seems to make order for free, but watching and deciding has a hidden cost.
In the 1860s, physicist James Clerk Maxwell proposed a thought experiment in which a tiny agent observes molecules in a gas and opens a door at just the right moments, seemingly creating order from randomness. The “demon” name itself was later popularized by Lord Kelvin, and the idea has teased the second law of thermodynamics ever since.
This game turns that idea into a control problem. Particles drift like a warm gas. A wall splits the box. You can’t move particles directly—you only open brief “windows” in the wall by clicking or tapping near it. Your goal is to increase the separation score as fast as possible (Reach %) or to maximize it within 60 seconds.