The goal of this challenge, is to get $75,000 (in available funds) in 2 in-game years (going by in-game seasonal calendar), thus earning the right to build your sim's house.

It's called house levels challenge, because along the road to riches, you must progress through homes by accumulated in-game available funds. Here is the chart for home levels.

Level 1: Trailer Trash
Acquired by: creating your family.
Lot rules: You must move into the trailer park found in the lot catalog, or in Belladonna Cove.

Level 2: Double Duplexes
Acquired by: gaining $20,000 in available funds
Lot rules: You must move into the duplex in the lot catalog.

Level 3: Tiny Townhouses
Acquired by: gaining 30,000 in available funds.
Lot rules: You must move into one of the NL small houses (any one will do.)

Level 4: Suburban Shack:
Acquired by: gaining $35,000 in available funds.
Lot rules: Any house that is worth more than $24,999 and less than $35,001 (remember that you gain money by selling your small house)

Level 5: Masterful Mansion
Acquired by: gaining $45,000 in available funds.
Lot rules: Any house worth more than $45,000.

Level 6: Crazy Construction
Acquired by: gaining $75,000 in available funds.
Congrats you've won!

Rules:
-No money, or motives cheats.
-No using the money printing reward.
-No mods that make money gain easier.
-You must start with exactly 2 people, one being fortune aspiration.
-You may use elixir of life, as it does not effect the timespan of the challenge.
-Only one adult can be employed at a time (including OFB business) but the other may learn and benefit from a trade. (ex. Painting, Gardening, etc.)
-You cannot sell objects that came with your house to help you advance your level.
-You cannot build additions to your house. You must earn the right to build mode.

Please post before and after pics.

Scoring:
+5 per child (They aren't a huge money pit, but cost some money)
+10 per any mod that makes money acquisition harder.
+15 if you buy a new outfit for your sims per each level.
+20 for every 1k spent.
+50 for every level achieved in the time limit.
+500 for winning the challenge.

very kool idea!

I'm actually starting to think 2 years (48 days) is too long.

Should I change it?

No, no, it's good like that! Gives your sims plenty of time to rack up the cash they need.

See, that's what I'm afraid of. What's the challenge, if you're almost certain to succeed?

Edit: On second thought, you can't use maxmotives, whicH should slow down career progression, and therefore income.

So, do your sims actually have to have that money available as cash? That would kind of mean that they had to earn $205,000 total, right? Or is it their household value rather than money in their account?

It is account money, but remember that you get a lot of your money back when selling the previous home.

parrot999 - So basically, it's account money plus the money your house is worth (visible from build and buy modes)?

No, but when you sell your house to get a new one, you get money for it, which over time will build up, so instead of having to get $205,000 total, you would need closer to $130,000. (rough estimate)

Aha, that makes sense! :-) Thank you!

Thanks for the clarification parrot. :D

I'll try this! It sounds very interesting and will make a great addition to my neighborhood as well as for my TS2 blog.
In case you want to follow my progress: https://xiang012.wixsite.com/thelatesimmer