Alright, let's see!
Main save: use cheats (UI Cheats will probably have it) to max out Green for my entire world, then turn off changes to it stays glorious (I'll have to see whether turning it off when Green is maxed out keeps it like that, or if I keep it on and just use cheats to keep it in that state). This is my utopia, basically.
Another save: this will be my testing save! I'll make a new Sim, start out in a starter home in Evergreen Harbour, and play out a greening storyline.
Dystopia save: another separate one! Turn Industrial all the way up then keep it there, use a bunch of absolutely glorious dystopian and cyberpunk builds I found on the Gallery, and play in San Myshuno with my favourite premades. Going to do this as a story on Instagram! (It won't be forum-suitable, sorry!) Also going to use the TOOL mod to add more industrial stuff, more garbage, et cetera, just for atmosphere.
Finally, runaway teen/aged down save: Also San Myshuno! This is a save I'm working on with a few others here, since I want to do a Runaway Teen challenge with Johnny Zest, but EL is going to add some great flavour to it. The griminess and dumpster diving will be a good part of it!
