This is the Survival Challenge. It takes place in a post-apocalyptic Willow Creek, but I recommend living in either Oasis Springs or Strangerville to get the effect.

Challenge Goal:
To successfully survive until Old Age takes its toll in an apocalyptic universe...

CAS Rules:
.You can only create one sim.
.You can only start as a Young Adult.
.You can make them look however you want, but I recommend dressing them in prehistoric CC as I did. I will link some below.
.You must have either the Freelance Botanist or Musical Genius aspiration.
.You must have both the Loves the Outdoors and Music Lover traits. The third trait is up to you.
.Once you're done with your main household, move them into a lot and create one household to place in every other lot in the neighborhood you chose. The rules above do not apply to these "neighbor households".

BB Rules:
.You can only have the following furniture at the beginning: A bed, a sink (no counter though), a toilet, a bathtub (no shower), a woodworking table, a guitar, and a packet of seeds (which type of seeds is up to you).
.You can't buy walls.
.You are not allowed to purchase any electronic devices or a fridge/stove/counters.
.Later on in the challenge, you can only purchase the following: More seeds, living things for your sims offspring, and more instruments (cheapest version only).

Gameplay Rules:
.You cannot have a job.
.You can only use the phone to travel.
.You are not allowed to leave the neighborhood.
.You are not allowed to visit any lots other than residential lots.
.You are not allowed to go on dates.
.The above rules (except for phone because that's anonymous) apply to neighbors as well. It's recommended that you remove all lots other than residential before starting the challenge, but not required.
.You are not allowed to have your female sims take pregnancy tests.
.Play on any lifespan length you choose.

Point System:
+15 points for every marriage
+10 points for every child born
+5 points for every child that becomes a child
+5 points for every child that becomes an adult
+5 points for every grandchild

-20 points for every divorce
-10 points for every toddler/baby that gets taken away
-15 points for every child/teen death
-20 points for every grandchild death
-100 points if you die of something other than Old Age

The challenge ends when your main sim dies.

Packs:
Get To Work
-Aliens are allowed
-Your sims can own businesses, but only to sell woodwork and vegetation

Vampires
-Vampires are not allowed

City Living
-You cannot choose to live in San Myshuno

Strangerville
-Use a cheat to complete the story immediately if you choose to live in Strangerville.

Dine Out
-Your sims cannot own restaurants

Cats and Dogs
-Your sims can have pets, but if your pets get sick there's nothing you can do about it.
-You cannot own or visit a vet clinic.

Seasons
-Your sims can have a flower arranging table/skill.
-Your sims can have a bee box
-You must start in Summer
-Season lengths can be any you wish.

Outdoor Retreat
-Your sims can have a firepit
-Your sims can have a tent instead of a bed
-Your sims cannot travel to Granite Falls

Jungle Adventure
-Your sims cannot travel to Selvadorada

Get Famous
-Your sims must be opted out of fame

If there are any questions, comments, or concerns, please comment below. You are welcome to share your stories of this challenge!

Prehistoric CC.

Other challenges by me:
The Life Challenge.
The Heir Challenge.

Want something more challenging? Why not try one, all, or some of these:
.Start with 0 Simoleans instead of 500
.Add another goal, like getting to Forgotten Grotto
.Playing with long lifespan