Hello! Welcome to the Full House Challenge!
I should note that although I haven't seen any challenges similar to this, there probably are. If this is a blatant copy, please let me know.

The premise for this is pretty simple, as it's basically working towards completing your sims' lifetime wishes, but there's a bit of a twist.

Setting up:
First, create your sims. You can have any number of sims, from 2 to 20 (althought probably not 20, that'd take way too much time). I tend to play with 8, but if you're more comfortable with less, that's fine. They can be anywhere from young adult to elder, but not younger.
Your sims can look however you want, there's no limitations. You can choose traits or randomise them, it's up to you.
However, when picking the lifetime wish, make sure you choose either a skill LTW or a career LTW, preferably the first option that comes up. Don't go choosing 'Super Popular' or anything like that, as keeping your sims on the home lot at all times is really the best way to play this.
Move your sims into any lot you want, you can use freerealestate, motherlode, kaching, etc. as really, money isn't an issue in this challenge. Make sure there are lots of skill items: chess boards, easels, musical instruments, etc. as your sims will need these in order to progress.
Once you have a home big enough for all of them, you can start the challenge.

The main rule is this: have your sims work towards completing their lifetime wishes, but by controlling only one sim at a time.
In other words, you may control one sim from 12am to 12am, one full sim day. Once midnight rolls around, no matter what your sim is doing, you must move onto the next sim.
You can go in order of age (this is what I do) or you can have your own system. It doesn't matter!

I suggest having all the sims with a career LTW joining that career as soon as you move them in, it means that while you're playing with another sim, they can all go off to their jobs. You can have the sims with a skill LTW joining careers as well, but this isn't necessary.

It goes without saying that Free Will needs to be on, otherwise your sims will stand there doing nothing when you're not controlling them. Aging can be set to whatever you feel most comfortable with. I usually play with it off, but if you want to make it more of a challenge you can try to make them complete their lifetime wishes before they age up or before they die.
Once a sim has completed their LTW, it's your choice whether you want to move them out of the house or if you want to keep them in and play with them still.
The challenge is over once every sim in your household has completed their lifetime wish.

I hope you enjoy it, and feel free to ask me any questions or keep me updated on your sims!
~Rebecca

Sound interesting. I might try it.