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 = 112 days (for now)

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)

Generations unlocked:

Gen 2: Growing Together - trait: Cheerful (unlocked in chapter 19)
Gen 3: ?

Traits and packs

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	Cats and Dogs
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
Hot headed		Werewolves
Kleptomaniac	For Rent
Lazy	Island Living
Loner	Life and Death
Loves Outdoors		Outdoor Retreat
Loyal	Cats and Dogs
Materialistic	Get Famous
Mean		Vampires
Music Lover	Get Together
Neat			Laundry day
Outgoing	Adventure Awaits
Perfectionist			Crystal Creations
Practice Makes Perfect	High School Years
Self-assured		Jungle Adventure
Slob			Laundry Day
Vegetarian	Eco Living
Squeamish (OR)	City Living

Reward unlocks - kits and stuff packs:

(Any generation) Completing the bodybuilding aspiration = Throwback Fit Kit
(Any generation) Maxing mixology skill = Cozy Bistro Kit
(Any generation) Maxing handiness skill = Restoration Workshop Kit
(Any generation) Completing the Big Happy Family Aspiration = Toddler Stuff
(Any generation) Completing the Painter Aspiration = Art Studio Kit
(Any generation) Living in a tiny house for a full sim year = Tiny Living Stuff Pack
(Base Game) First generation aging up to elders = Golden Years Kit
(Seasons) Completing Freelance Botanist Aspiration = Greenhouse Haven Kit
(Seasons) Maxing gardening skill AND flower arranging skill = Blooming Rooms Kit
(Outdoor Retreat) Completing the Outdoor Enthusiast aspiration = Happy Little Camper Kit
TBA as I play along

Creek Tales - A Pack Legacy Challenge

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