The hidden puzzle you're referring to in Chapter 4 of Portal 2 requires some tricky maneuvers, but it's definitely solvable. Here's a step-by-step guide: 1. **Start by locating the puzzle**: The first thing you need to do is to actually find the puzzle. It's located in the room with the Propulsion Gel which makes you run faster. 2. **Locate the weighted storage cube**: After entering the room, turn right, the weighted storage cube is across the room. Notice that there is a floor button on your side. This button controls a set of stairs on the other side. 3. **Use the propulsion gel**: To get across, you need to use the speedy propulsion gel to run across the gap quickly, before the steps fold up. However, you'll notice that when you step on the button, the wall that you would usually use to bounce against for momentum is covered in Conversion Gel (the white gel), and you won't have enough momentum to get across with just that short run-up. To solve this, you have to put Conversion Gel on the floor also. 4. **Procedure**: To do that, aim a portal at the angled wall panel to the right of the Propulsion Gel's output. Then, step on the button yourself. This will make the Propulsion Gel go through your blue portal and splat against the orange portal on the wall on the other side. Most of the Propulsion Gel will stay on the stairs but some should slide down to your side. 5. **Retracing steps**: Now, go up the stairs again, put your blue portal back underneath the Propulsion Gel's output and run onto the floor button. The Propulsion Gel will coat the floor leading up to the gap. 6. **Run, jump, and repeat**: Finally, make your run up on the Propulsion Gel-ed floor and into your orange portal. This will spit you out of the blue portal near the button, and if you timed it right, you can run off the edge before the stairs fold up, pressure the button down and release a new cube. To get the cube to your side, simply use the portal to transport the cube back to your side. 7. **Solving the cube/button puzzle**: To solve the puzzle, you need to use one cube to hold down the button that keeps the stairs extended, allowing you to run across to the other cube. However, the cube on the other side is behind a door that only opens for a second when you step off the button. So you have to use some Propulsion Gel to slide the extra cube into the button just as you're running across. The trickiest part is getting the timing right, but with a little practice, any player can solve this hidden puzzle in Portal 2. Please remember that in order to solve this puzzle, careful observation of your surroundings, smart placement of your portals, and good timing are key principles! I hope this was helpful. Happy gaming!