I may or may not try the video game thing. Spending time is easy, spending lots of consecutive time is more costly. :) I have taken walks as you describe, except in unfamiliar areas but where I don't expect to run into things all the time. I don't see my surroundings, I just know where they are approximately (and they update when I move). My guess is that visualizing something from nothing is also part of the spectrum...? I definitely had more success with visualizing fully-featured scenes (they end up mostly as not-quite amorphous blobs but totally in the right place and kinda painted over with Imagination) than geometry.
I would guess walks in familiar areas (e.g. common routes within your house/apartment) would be more helpful. Since you see a lot of the same imagery it may help your imagination fill in the details. again be careful walking around with eyes closed.
another thing that could help is visualization by parts. work on getting just one piece clear in your mind before gradually expanding on that, and maybe with practice you can put the pieces together more quickly.
Previously: Generalizing From One Example
Summary: I do not have visual mental imagery. I want it. How do I get it? What exercises, if any, will help?
In further detail... Here's Francis Galton's Statistics of Mental Imagery paper. I'm not quite at the 3% level of completely unable to form mental images, but I'm close. In particular there are three times I have vivid, sharp mental imagery, and the existence of such times tells me I have the brain hardware to visualize. It's enough to let me know that I want it all the time. Unfortunately I don't know how to get it. And searching online has proven difficult and frustrating... for example this article is first of all about a different meaning of "visualize", it's talking about some kind of self-help motivational thingy, and second of all it starts by saying "How to Visualize: I want you to relax and close your eyes. Picture a hot, sunny day at the beach."
Full Stop. Halt, Catch Fire and Burn.
That's already too far. For those of us who don't visualize, practice definitely does not consist of pulling up mental images, playing with them in new ways, and expanding our imagination. I'm very good at imagination in some ways, but I lack that first ability to pull up a mental image. That's what I want to learn how to have!
Here is a description of what I can do, what I have tried, what I have learned, etc.
I see vivid visual mental imagery in 3 situations: