Reminds me of the Queen’s Gambit where the protagonist plays chess on a hallucinated chess board projected on the ceiling.
What you do is you speak out loud what you see "A purple blob in the middle, it's moving to the right, now it's morphing into a more green blob" etc
If you do this for a couple of minutes what you will see in your closed eyes will become more shape-like "the blob is now more circular. It's back to a blob again, now it sort of resembles a weird pillow"
Somehow, the feedback loop of objectively describing out loud what you're seeing trains the brain to fantasize more real shapes and objects.
Try it out if this sounds interesting to you!
But it can get really dark as well. I have done this between 10-20 times on my own, and the one time the visuals are about like... fruit, and the other time they're about really really bad super shameful and traumatic personal experiences.
It's not necessarily a game, although I can imagine it has the potential to be one. The danger is that this requires you to speak up about anything that comes to mind, and sometimes your mind will wander to very serious memories or pictures.
I can say that it works incredibly well though. The purpose of image streaming is that it should improve your ability to imagine shaped in your head, and it works _really, really well_. I personally stopped because I didn't feel comfortable speaking out loud many of the things I saw (even when I was alone), it involves "confronting your shadow" in Jungian terms
Here's the inventor's article on it by the way: http://www.winwenger.com/imstream.htm
^1: the person who invented it says it has something to do with how the feedback loop is more real if there is real consequence to what you say iirc