Heyo, I am CAMFAM2018 and I am very excited to bring to the Simming Community my very own idea for a TS4 Challenge!
Here's the idea: The First Four Challenge.

The "The First Four Challenge," is a TS4 Challenge in which you begin with a completely blank world with no other lots or other households besides the one(1) lot with the one(1) household containing "The First Four" Sims, and the ultimate goal is to populate and build an entire TS4 game with your own creations of Sims and builds!

Rules:

• "The First Four" must contain only four(4) Sims at the start.
• "The First Four" must be comprised of two female and two male Sims at the start.
• You must not have any cats, dogs, robots, or ghosts in "The First Four" household at the start.
• You must delete all pre-existing lots and households before play can officially begin.
• You must set "The First Four"'s household funds to $0 before play can officially begin.
• You must not use cheats past setting "The First Four"'s household funds to $0.
• You must wait at least one(1) Season or fourteen(14) days to Age-up any Sim.
• All lots must have the "Off-the-Grid" trait until your "The First Four Challenge" Game Save has a population of at least ten(10) Sims.
• You must not visit any un-editable lot(s) such as hospitals, playgrounds, or food stands until your "The First Four Challenge" Game Save has a population of at least ten(10) Sims.
• You must not send any Sims on vacation until your "The First Four Challenge" Game Save has a population of at least ten(10) Sims.
• You must not adopt a kid (or kids) or a pet (or pets) until your "The First Four Challenge" Game Save has a population of at least ten(10) Sims.
• You must not get a job until your "The First Four Challenge" Game Save has a population of at least ten(10) Sims.
• You must not build any type of un-ownable lot(s) such as bars, libraries, or beaches until your "The First Four Challenge" Game Save has a population of at least ten(10) Sims.
• You must not send any Sims to University until your "The First Four Challenge" Game Save has a population of at least twenty-five(25) Sims.
• You must not have any Sims live in an apartment (or apartments) or a dorm (or dormitories) until your "The First Four Challenge" Game Save has a population of at least twenty-five(25) Sims.
• You must buy and decorate any Retail lot(s) such as restaurants, stores, or bakeries with household funds.
• You must not import any Sim(s), lot(s), room(s), or anything else from the TS4 Gallery.
• You must build everything by yourself in Build Mode.
• You must not create any more than "The First Four" Sims in CAS.
• You must create "The First Four" Sims.

Have fun!

Tips:

• Have Sims fish, dig, and collect treasures to then sell in order to make Simoleons before they are allowed to get jobs.
• Once Sims have enough Simoleons, first have them set a bit aside for bills, then use any extra cash for necessities such as food and a toilet.
• In order to set "The First Four"'s household funds to $0: Hold Ctrl+Shift+C, type into the cheat input box "testingcheats on," type into the cheat input box "money 0," and hit Esc to close the cheat input box.
• In order to disable cheats past setting "The First Four"'s household funds to $0: Hold Ctrl+Shift+C, type into the cheat input box "testingcheats off," and hit Esc to close the cheat input box.
• Do not have only one(1) female "First Four" Sim have children or marry with both(2) male "First Four" Sims. This is because if their kids are even half siblings, they can not become romantic with each other or later have any offspring together.
• If you ever want Magical Sims in "The First Four Challenge," you must make at least one(1) of "The First Four" Sims Magical. This is because with the lack of pre-made Sages you will have no way of getting Magical Sims, unless an offspring inherits Magical abilities from a parent.
• If you ever want Vampire Sims in "The First Four Challenge," you must make at least one(1) of "The First Four" Sims a Vampire. This is because with the lack of pre-made Vampire Sims you will have no way of getting Vampiric Sims, unless an offspring inherits Vampirism from a parent.

*Please: Give credit to CAMFAM2018 if you reference "The First Four Challenge" with any idea, material, or concept in any form of media. Thank you.*

P.S. Check out my(CAMFAM2018) "First Four" Sims(along with many other fun creations!) on the TS4 Gallery for inspiration! I will try to keep updating and adding to this thread/discussion about "The First Four Challenge" if I see it fit. And I will also try to answer any questions here on The Sims Forums if anyone has them about anything here or somewhere else that may concern CAMFAM2018. Have a great day & happy Simming!