When Maxis introduced the option of turning packs off and on in game, I was wildly tempted to create a Pack Legacy Challenge for the game. Of course, someone else already did, but as usual, I'm all about creating my own rules based on my own playing style and play badly when others dictate my game, which of course means I'll make the rules up as I go, still there are a few basics.

Basic guidelines I intend follow:

I will start with an entirely base game family, the Creek-family (introduced below). They (including the kids) are generation 1 of this challenge.
With every new generation at least one new pack (EP, GP, SP or Kit) will be unlocked. That generation then has to truly explore that pack, meaning jobs, looks, decorations, aspirations, traits, skills even deaths should be explored to the fullest by the sims born in that generation.
The exception is seasons, which will be unlocked as the oldest child of gen 1, Willow, ages up to a teen.
Which pack that will be unlocked will depend on the first trait given to the first child in the next generation.
Kits and some stuff packs are treated differently, added as rewards when certain aspirations are completed or certain skills maxed out. Some will be opened together with other packs.

And some rules (yes, even I have a few rules):

Traits will generally be given randomly, with two exceptions. 1) In each family no one should share the same traits, and as far as possible I'll try to randomize between traits not yet played with. 2) A sim of a new generation MUST take traits of a newly unlocked pack if there are any first.
When the first child of the next generation receive their first trait, true randomness applies as that will dictate the next pack to unlock.
No CC is allowed, a part from the occasional ad-on pack (separations of items already in game, matching chairs to a sofa or more window options). Even add-ons should be kept to a minimum. This is after all about exploring the packs to their fullest.
Mods are allowed, but not those that significantly adds gameplay options (such as career-mods, new aspirations, traits or new gameplay). The purpose here is to explore the options of the packs after all.

Aging:

I tried normal aging, that didn't go over well, so there is what I am using at the moment (based on a 7 day length of season and 28 day year)

Baby+infant+toddler = 28 days

Child = 28 days

Teen = 28 days

YA = 56 days

Adults = 150 days

Elders = 56 days

Unlocking Packs:

The main idea is that packs will be unlocked based on personality traits of the sim, with a child sims' first trait being the trigger for which pack to unlock while their aging up to teens triggering the unlocking itself.

Not all traits are allowed for kids however, and some kits and stuff packs are not large enough in warranting them an entire generations, and these packs will either be tied to a bigger pack or opened in a sort of rewards system.

BG-family: Starting point:

Basegame + Holiday free stuff

On Willow aging up to teen

Seasons + autumn apparel (Chapter 5)

Gameplay unlocks:

Outdoor Retreat was unlocked for gameplay reasons after Candice was cursed (unlocked in chapter 13)
My Wedding Stories was unlocked when Carolyn Landgraab demanded a fancy wedding (unlocked after chapter 26)

Generations unlocked:

Gen 2: Growing Together - trait: Cheerful (unlocked in chapter 19)
Gen 3.1 (Valentine): Vampires - trait: Mean (unlocked in chapter 36)
Gen 3.2 (Link): Cats and Dogs - trait: Cheerful (unlocked in chapter 38)

Traits and packs (updated after vampire pack was triggered)

When the eldest child of a new generation gets their first randomised trait, that will trigger a pack to be unlocked. Once a pack has been unlocked a new list with traits connected to packs will be made to account both for new traits and for removing packs that are already opened.

Trait	Expansion Pack	Game Pack	Stuff Pack
Active	Snowy Escape
Active Imagination (only for kids)	Adventure Awaits
Art-lover	City Living
Bookworm	Discover University
Cheerful	Get Together
Creative		Dream Home Decorator
Erratic		Strangerville
Evil		Realm of Magic
Geek	High School Years
Genius	Discover University
Gloomy	Life and Death
Glutton		Dine Out
Good	Get to work
Goofball		Parenthood
Heart on your sleeve	Lovestruck
Hot headed		Werewolves
Kleptomaniac	For Rent
Lazy	Island Living
Loner	Life and Death
Loves Outdoors	Horse Ranch
Loyal	Parenthood
Materialistic	Get Famous
Mean	Lovestruck
Music Lover	Get Together
Neat			Laundry day (+bust the dust)
Outgoing	Adventure Awaits
Perfectionist			Crystal Creations
Practice Makes Perfect	High School Years
Self-assured		Jungle Adventure
Slob			Laundry Day (+bust the dust)
Vegetarian	Eco Living
Squeamish (OR)	City Living
Cat Lover (C&D)	Cottage Living
Dog Lover (C&D)	Horse Ranch

Reward unlocks - kits and stuff packs:

NOTE: Not all aspirations are represented, and only packs I own are included. Packs that are still locked will be added as they are unlocked.

Accomplishment	Which Stuff pack/kit is unlocked.	Required Pack	Who unlocked it
Basegame:
Completing the Bodybuilder Aspiration	Throwback Fit Kit	BG
Completing the Bestselling Author Aspiration	Book Nook Kit	BG
Completing the Musical Genius Aspiration	Music Den	BG
Completing the Painter Extraordinaire Aspiration	Artist Studio Kit	BG	Christmas
Completing the Big Happy Family Aspiration	Toddler Stuff	BG
Completing the Successful Lineage Aspiration	Kids Room	BG
Completing the Master Chef Aspiration	Cool Kitchen	BG
Completing the Master Mixologist Aspiration	Cozy Bistro Kit	BG
Completing the Fabulously Wealthy Aspiration	Secret Sanctuary Kit	BG
Completing the Mansion Baron Aspiraton	Décor to the Max Kit	BG
Completing the Computer Whiz Aspiration	Casanova Cave Kit	BG
Maxing out Handiness and completing the Nerd Brain Aspiration	Restoration Workshop Kit	BG	Sandy
Completing the Renaissance Sim Aspiration	Everyday Clutter Kit	BG
Completing the Serial Romantic OR Romantic Explorer OR Paragon Partner Aspiration	Simtimates Collection Kit	BG/LS
Completing the Soulmate Aspiration	Romantic Garden	BG	Jamie
Completing the Freelance Botanist Aspiration	Greenhouse Haven Kit	BG	Willow
Completing the Curator Aspiration	Basement Treasures Kit	BG
Completing the Jokestar Aspiration	Backyard Stuff	BG
Completing the Neighborhood Confidante OR Friend of the World Aspiration	Bowling Night	BG
Completing the Party Animal Aspiration	Luxury Party	BG
Reach the top of the Trend Setter Career while also mastering photography	Moschino	BG
Live in a Tiny House for a full sim-year	Tiny Living	BG
Maxing both the Gardening and the Flower Arranging skill with the same sim	Blooming Rooms Kit	Seasons	Willow
Completing the Outdoor Enthusiast Aspiration	Little Campers Kit	OR	Willow
Completing the bottles collection	Riviera Retreat Kit	MWS
Completing any Vampire Aspiration	Storybook Nursery Kit	Vampires
Completing the Friends of Animals Aspiration	My First Pet	C&D

Creek Tales - A Pack Legacy Challenge

Creek Tales - A Pack Legacy Challenge (Rules and Guidelines)