I know I already post this, but this is a more organized description, with a few changes on how it should be played. Also, since this should be played with the intented BACC incorporation, I recommend doing that for more interesting and challenging (after all -- this is a 'challenge') gameplay.
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• All objects are locked, except for those listed below this bullet point, meaning that you can't buy them from the buy mode category when you start the game.

- By default, the objects that are unlocked is a telephone and a wall or any kind of end table to support the electronic object, the very cheapest full size fridge and (if you have a pet) a pet bowl, and (optional) any object that produces items or not, but does allow your sim to earn money (pottery table, easel, robot crafting station, ect.).

• Build mode objects and tools are locked as well, except for terrain tools&paint, gardening essentials.

- In a scenario, you may build one wall title only when for the sake of supporting one or two objects that require to be attached on it (eg. mirrow, toilet).

• In owned community lots, you can buy and place down any objects from the buy&build mode catalog, regardless whenever it is lock or not.
• To unlock a specific object, one of the household must establish a shop/store in a real state and put the exact object on sale (meaning for instamce the same brand tv won't unlock if you place a cheat or exensive /& different-looking tv).
• Sims must only purchase the objects from the owned community lots that sell them, unless when required quickly in an emergency event or the household owns the store/shop that sells them - then you can enter the buy mode.
• One lot can only have one established store, which are listed below this bulletpoint.

-These can be an electronics, plumbing, furniture, lightning, deco/sourvenir store, pet store, and car dealership.

• A lot can have a mall, that consists of these sold items in shops: flower, toy-store, recreation, sport goods, bookstore, clothes, grocery and party + as an additonal one store from the above list.
• One real estate can be bought per household.
• To unlock the following service, you must complete the following task:

- Pizza&Chinese Delivery: establish a restaurant (or for base games - tons tables/island-counter and chairs/stools with the replacement of stove and fridge over chef stove).
- Repair Service: a sim (in the neighborhood) with max out mechanical skill.
- Maid: a sim with max out mechanical skill.
- Butler: same requirement as Maid’s, but also cooking is a must.
- Pet Adoption Service: a pet store with pets put up for sell.
- Gardener: a sim w/ golden badge or reaching the needed population number.
- Other: reaching the needed population number.

*Later on I will be explaining on how you unlock each build mode objects & tools.*

ETA1: To clarify, for a household hire the respective npc service, the sim with the necessary skill(s)/requirements that isn't played must reside in the neighborhood. So for instance, If there is only one sim in the neighborhood that has maxed cleaning skill and (s)he dies, none of the neighborhoods may hire him/her.

Goal: What BACC suggests + unlock all buy&build mode objects and tools!

Nice ! i have tried alot of BACC , but they all ended up as an Legacy ... LOL

For Unlocking Build Mode tools/objects, you must have at least one sim in either Architecture career or (If you don't have Freetime) Business career reach the corresponding levels:

Architecture

1. Head of Construction Company ~ Roofing, wall covering, flooring, doors, arches, windows.
2. Draftsman ~ Foundation, stairs, railling, fence and gates.
3. Architect ~ Awnings and columns.
4. Master Architect ~ Elevators.
5. City Planner ~ Swimming pools, fireplace.

Business

1. Junior Executive ~ Roofing, wall covering, flooring, doors, arches, windows.
2. Senior Manager ~ Foundation, stairs, railling, fence and gates.
3. Vice President ~ Awnings and columns.
4. CEO ~ Elevators.
5. Business Tychoon ~ Swimming pools, fireplace.

If I forgot to mention some other left out Build Mode tools/objects, then consider reaching the top of the career to-be 'unlocks all objects'

hi ! how can we unlock more families ? we start with 1 family or ? how do we unlock the subhoods , downtown , vacation ones etc . ?

You follow Icad's rules: http://modthesims.info/showthread.php?t=335049

I would try this in Sims 3... But then I'd have cellphone by default. I wonder how that'll work...

Taikajamppa, you would have to use nraas retuner to disable the phone. For sims 3, I play the Apocalypse challenge and no cell phones.

There's really no difference. Both function the same, so both: the telephone and cellphone should be unlock and by your hand.

The Build-a-City Challenge is by clintcasey85, as mentioned in the post you linked to. The rules are here.

I didn't based my challenged out of original creator: clintcasey85. I based it of @iCad.

New idea: for those who get bored living in puberty with the starter sim/family, you can switch things around by creating a few more household/sims via die throw to determine how many you add. You can have them be excluded from the rules, except for being played rotionally and creating families (however, you can adopt animals and invite someone to be your npc roomates).