I've tried the hold-the-spacebar, left-click-mouse thing, on everything I can think of (the rainbow-beam buildings, the telescope, the thing in the center, the pile of rocks in the lower right corner of the map...) and nothing does everything. It feels like I'm missing something, like there's something I need to do first, or I'm clicking on the wrong things?
Funny story. (Not really.) It turns out my trackpad settings were keeping me from clicking while a key was pressed. Once I turned that off, things made a lot more sense.
Anyway, that's how I destroyed the entire world and got ending B. Kind of a bummer. Trying to decide if I have the energy to go through it all again...but it's very cool in any case.