Ganzfeld Ascent
A dim, near-uniform field. Hold perfectly still — don't move the pointer or the device — and your own visual noise accretes up a hallucination hierarchy: phosphene dots, then cobweb lattices, then proto-faces. Any motion breaks the trance.
Sound starts on this click (browsers block autoplay). Then be still and watch the field organize itself — or just wait: with no interaction it self-drives the ascent so you can see all three stages.