Find more recent posts about Sims 4 build challenges and shell challenges and CAS challenges here!
From The Sims, due 1/13/2020:
Be sure to read all of the details in the thread!
Something a little different: The 12 Days of Simsmas with little challenges added daily from December 25 to January 5, 2020. Check it out here: https://forums.thesims.com/en_US/discussion/970507/12-days-of-simsmas-3rd-edition
Check often! The post is updated as I learn of other challenges.
Build Challenges:
From Sims Community, due 12/27/2019:
“Biweekly I will post a selection of images and links for the Simming Community to replicate in-game and post to the gallery or on social media using #ReplicaChallenge (Open to console Simmers!).”
https://simscommunity.info/2019/12/13/the-sims-4-replica-build-challenge/
From Ninnster, due 12/27/2019:
From Sim_Michele, due 1/2/20:
From The Sims, due 1/13/2020:
Be sure to read all of the details in the thread!
From NelsBuilds, due 1/13/20:
From Taoron, due 1/13/2020:
The Homes in Literature Build Challenge 2: A Farewell to Arms by Ernest Hemmingway
From ScarfyLove, due 1/15/2020:
From FruUtter, due 1/19/2020:
A tiny house challenge–find out more here!
From Reddit, due 1/25/2020:
From ArsenGirlGaming, due 1/28/2020:
From Phirehero, tours on 1/30/2020:
From FireflyGamer107, due 1/30/2020:
On the official forums, build a debt collector’s house. Find more information here!
From Build n Share, due 1/31/2020:
Tears of a Clown: a home for 74K using 4 shipping containers
From Ninnster00, due 2/1/2020:
From luckyheather, due 2/1/2020:
From SimplyUnique, due around the end of January:
Create a build using only the furniture provided.
From Sim_Michele, due 2/6/2020:
From Taoron, due 2/12/2020:
The Homes in Literature Build Challenge: Little House on the Prairie
Find more information on the official forums, here!
From Jir, tours on 2/17/2020:
Room Challenges:
From Rosemow, due 1/7/20 by 7 PM PT:
The theme for the week is : two color bright bathroom
https://forums.thesims.com/en_US/discussion/comment/13311085/#Comment_13311085
From Rosemow, due 1/7/20 by 7 PM PT:
The theme for the week is : two color bright bathroom
https://forums.thesims.com/en_US/discussion/comment/13311085/#Comment_13311085
From Taoron, due 1/13/2020:
The Homes in Literature Build Challenge 2: A Farewell to Arms by Ernest Hemmingway
From IamJackPreston, no due date listed but around 1/21/2020:
From Rosemow, due 1/21/2020:
On the official forum, create an animal themed bedroom or study. Read more here!
From Build n Share, due 1/31/2020:
Tears of a Clown: a home for 74K using 4 shipping containers. Create the master/guest bath.
From OddSocksTango, due 2/11/2020:
“Our first Community House Challenge theme of 2020 is Martian Space Colony!”
From Taoron, due 2/12/2020:
From Artorsims, no deadline:
Shell Challenges:
From SphereArcana, due 1/1/20:
From JazzyRoseee, due 1/4/2020:
From RealThomasTV1, due 1/10/2020:
From TheSimsReaper, tours on 1/10/2020:
From EmUniverse, tours on 1/12/2020:
From AvelineSims, due 1/15/2020:
From JadeNchanted, tours on 1/15/2020:
From Zefrine_TV, deadline 1/18/2020:
https://athena.thesims.com/v1/images/1/0x000007cd/67EC7CB3-2B8F-11EA-8D71-2495E2BB44F7/00.jpg
From NelsBuilds, due 1/20/20:
https://nelsbuilds.com/build-challenges/
From Anchesenamon Sims, due 1/20/2020:
From RynAsInWin, tours on 1/21/2020:
From The Siminary, due 1/24/2020:
From ElocineCinQuatre, due 1/31/2020:
“Make a 2 bedroom/2bathroom home”
Download here!
From TheSimmingSpoonie, due 1/31/2020:
From AlJay, due 1/31/2020:
On the official forums, find this blueprint/shell challenge. The blueprint is provided–this one is for a small home. Start from scratch or use the provided shell. More information here!
From hiphiprenee, tours on 2/7/2020:
From The Sims Reaper, due 2/16/2020:
From EmUniverse, due 2/16/2020:
From GemstoneSimmer1, due sometime around 2/2020:
From lilsimsie, deadline to be announced:
From Cypriano3, no deadline:
From Julie1112, no deadline:
From lukeydean, no due date:
From lilsimsie, no deadline:
Not really a challenge; a shell from lilsimsie to decorate here!
Furnish Me Challenges:
From Pixelheart27, due 1/13/20:
From JazminesSim, due on 1/13/2020:
From Sim_Michele, due 1/16/20:
Screenshot Challenges:
From BrennachanSims, due 1/16/2020:
An opportunity to win the Laundry Day Stuff Pack!
Create-a-Sim/CAS Challenges:
From jadeybabez86, due 12/30/2019:
Download here!
From curlangel75, due 12/31/2019:
New Year’s Eve Party Challenge: find the rules and more here!
https://athena.thesims.com/v1/images/0/0x00002596/ADA0E8E8-28A7-11EA-8688-BA891CD6F027/01.jpg
From SilvieSIMS12, due 1/1/2020:
“I am hosting a new challenge, it is the Winter formal! Where everyone has fun and dances!”
Find it here!
From Sims4Sarah, due 1/1/2020:
Check it out here!
From Sims3TestAlias1, due 1/2/2020:
“Style this sim for the New Years party (the first outfit)”
Download here!
From Cypriano3, due 1/4/2020:
Find the rules and more here!
https://athena.thesims.com/v1/images/0/0x00001e60/C8F79307-2A77-11EA-8607-4BBF48D73738/00.jpg
From Doddizumms, due 1/9/2020:
Find the info for the Zombie Challenge here!
From Glovely and Frogpizzaz, due 1/11/20:
From Taoron, due 1/13/2020:
The Homes in Literature Build Challenge 2: A Farewell to Arms by Ernest Hemmingway
From ScarfyLove, due 1/15/2020:
See more here!
From GLovely1 and KSsDesign, due 1/25/2020:
A wedding love challenge! Find more information here!
From PineappleDuckLOL, due 1/31/2020:
An annoying Sim! Find more info here!
https://athena.thesims.com/v1/images/0/0x00001bce/A36B0388-2CF6-11EA-8675-F3DBDD0CBB2C/00.jpg
From LisaBeeSims, due 1/31/2020:
From Build n Share, due 1/31/2020:
Tears of a Clown: Create the client, Ash Rushford and his clown persona, and Emily.
From Sims4Sarah, due 2/1/2020:
See more here!
From icn89, due 2/1/2020:
Make a base sim. Find out more here!
From Taoron, due 2/12/2020:
From jadeybabez86, due 2/28/2020:
Find more information here!
From 6th-Juice, no due date:
Candy Challenge. See more here!
From PineappleDuckLOL, no due date shown:
“Make a lady intrested in Carl” Find more info here!
From SimmerBoi, ongoing:
Create Sims that may appear in the next story! Young adults to elder, villains welcome.
From Popee2017, no due date listed:
Simlit Challenges:
From LisaBeeSims, due 1/31/2020:
This is bit different than usual! You’ll find the information you need here!
Big list of ongoing game play, CAS, and build challenges The Sims 4 on the official The Sims Forums
Built With Love Sims 4 
Wow, that’s a lot of challenges going on. Some I’ve already entered and / or am busy with, but also so many others from creators I don’t know (but that’s about to change). Thanks for this great list, Julien!
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