I have a very ambitious goal, one which I have been working towards since 2013. My goal consists of three (x3) major sections.
1- To Create Living Worlds
To create the 'Living World' which EA describes in the owner's manual. These worlds are ones which are varied and dynamic. They are shaped by the collective society (community) of its residents. These are places where Sims can truly autonomously 'live' according to their own wants and desires. Every thing I add to these worlds, I place there for Sims autonomous use (or not). I remove myself from their equation.
2- Allow Sims to Naturally Progress and Develop
I develop Sims according to who they show themselves to be instead of what the sum total of their traits, LTW or job tries to 'force' them to be. This process is too detailed to go into on this thread. I will say that it has taken a long time to straighten out many of the messes The Sim's Team made when they created the Townies; and I still have many left to go.
3- Tell Their Story
And finally, to unify the lore of their collective stories based on what is written as fact from their creators (The Sims Team, Maxis and Electronic Arts). There are so many super hidden clues which lead to the potential for a solid linear story about the state and history of SimNation as it is in their current time.