I've been working on this challenge for a while now, and it's finally done! It is a huge challenge, meant to last for months or even years. You start with a completely empty save file, and by the end your world is completely full with sims you've made and played with, their houses, and community lots you've built or picked from the gallery.
It can be played with the base game alone, but has rules for all the packs.
The idea is that you use your households to unlock the community lots, which then let you add more households and unlock even more community lots. I've laid out all the rules in detail on this blog: https://buildaworldchallenge.blogspot.com/
I also created a spreadsheet that you can use to keep track of everything and automatically shows what you've unlocked, which can be found on the blog as well. I started playing through the challenge myself, and have made a few blog posts about my starting households.
I would love any feedback from folks on the challenge and the rules, and whether anything needs to be clarified or could be improved.
Wow, this is very thought through, and if I weren't already deep into my own world building for rotating household purposes, this would be the challenge for me! The rules looks easy to comprehend I think, and I really like that you've centered it around the community lots, I find those much more interesting than residentials. The sim Denise looks very handsome in her outfit too.
A tip for lot assignments:
What I've done in my save is make use of the Residential lot to create all sorts of real life public venues, that the game, yet, have no distinct assignment for. So a 'hospital' is a Residential, with a live in doctor and nurse, in a house built as a medical clinic; a 'graveyard' is a Residential (Haunted House) with a live in grave keeper (and ghost roommates), built like a park like grave yard with a crypt; a 'prison' is a residential with a live in guard, and some inmates as roommates, and the build appropriately structured; a 'daycare' a residential with the day care personnel living there etc. The game allows for a lot of flexibility, and small features can be used to make it seem and act realistic.
The EL lot Community Space, designated a Community Garden, can be used as a place for all sims to access harvestables (a functioning community garden); the lot Museum I've used for cinema, and I'll build a church for congregations with this as well. Etc.