

Ideally I'd recommend Seasons + Generations + University Life for a "complete" experience. but other than some admittingly nice but non-vital additions, none of these EPs is needed for enjoying the game. Every other EPs are just catering to your different tastes. Without the EPs however, you don't get Seasons which I do believe enhances the game greatly and give it a lot more variety. The simish interactions are still there and so is the pool. But you can export your household and import them when starting in a new town (I think you don't get to keep their special traits and the funds however). You are, however, mostly confined to the town you started in.

The EPs do add to the experience, but you still get the open world life sim without them.
