I guess I wouldn't call it rules but here is my gameplay style.
I chose a empty template and made a new world named Sanders. I made 14 base families and built all their houses myself. I put down pre-made costum/in-game lots because I don't have the patience lol.
My neighbourhood is soon gonna be 3years old. 400 sims. All made via Try for Baby, except when I feel like I wanna add some new looks so I create families which isn't often.
Here is I guess what I would kinda consider rules.
1. No cheats;
2. Same gens should be very close-by in age;
3. No deleting tombs;
4. No adding money to my sims;( exluding Brokestoon which houses the sims that aren't the most well off financially, so I make a family, the cheapest house ever, make their funds 0, and make them build up their house and life, and I use online banking which is awesome because every sim can save up money and I can take a loan if I really need one.)
5. Play every family equally, no matter if I like them or not.
I don't know how many people would have the patience to play a neighbourhood for 3years but it doesn't get boring and the family trees are a sight. My 1st pair of 1st gens just died 4months ago so that should give you a idea of how many sims I have (400) to play. They were my fave sims too.