Also if you have any small thing you discovered on your own and it blew your mind feel free to share that.
It took me about a year or two to notice that the timed explosive blocks have an animation of a timer on them (not the number display).
Due to creative efforts lately I've discovered a few other things, such as that lovely, verdant, dusky, and military color schemes are just hue shifts of each other. I also discovered that the sanctuary music has a very faint whitespace swarm music playing slowly and softly in the background.
What seems to be Deconstruction Zones in the skybox (skysphere?).
It took a long gaze off of one of the Dark City's broken roads for me to actually notice them.