Here's a new challenge for you. It's a re-population challenge.
Storyline: You have 5 Sims. They are all young adults. There should be two boys and three girls or two girls and three boys. They come from the planet ACK. They landed on the Sims planet and it is their job to re-populate all of the worlds in Sims.

Rules:
- Delete all households and lots including pubs and parks etc
-Fill one house (of any size) with men. These are Pappaz.
-Pappaz must have the following traits: Romantic, Outgoing and any other of your choice and the aspiration doesn't matter as they will not be played, only used
-Fill another house (preferably of the same size) with women. These are Mammaz.
-Mammaz must have the following traits: Romantic, Outgoing and another of your choice and the aspiration does not matter as they will not be played, only used
-The Boggies must meet up with these Mammaz and Pappaz and have children with them
-Turn aging off unplayed households and when you move in Boggie children, mark the households as unplayed
-Keep the children with you until they age up to young adult then move them out
-Boggies don't get careers
-Sims become inactive (can't have kids, because of risk of death by woohoo) when they are Elders
-If all Boggies die or become inactive, pass on to one of the Boggie children
-Every Boggie must have the traits Romantic, Outgoing and any other of your choice and the aspiration Serial Romantic
-The aim is to re-populate all of the worlds with Boggies to create a "perfect" society
-Feel free to use the following cheats: money, building, reset, debug, cas
-If all of the Mammaz/Pappaz become inactive, deal with it. Make do with your own children
-To really give it the Alien feel, use aliens (if you own Get to Work) or make them a strange color such as blue, green or red.

Enjoy and tell me if there is anything wrong with the challenge.

UPDATE (courtesy of Walpster ) = It is recommended you have MC Command Centre to stop townies spawning. (But you don't have to)

This sounds great! But, why do you have to immediately age up the teen Boggies?

Also, is it possible to make the Boogies into siblings? Like, the main household.

(Ok last question I SWEAR, I only realised i should ask this after i posted :/) Is it super necessary to delete all parks and bars and that stuff?

Yeah! That would be fine! In fact, I'll edit the rules, it makes it a lot less complicated

Well, I guess you don't have to, feel free to shape the rules to fit your playing style

Well, it was so they could get pregnant/impregnate someone (unless you have a teen pregnancy mod).

I don't have that, but it sounds like a pretty good mod! I'm Loving the challenge so far: I made all of the townies (Who, BTW, keep respawing after deletion which is really annoying) into service droids!

Wow! That sounds annoying!

Maybe you can recommend people a mod like the MC Command centre, or any real 'master controller' mod that gives an option to disable townie's from spawning?

Yeah, sure! I'll add that in.