It helps that it's shaped more like townhouses than an apartment building. We have a large interior carpark/garden where the kids play, which creates a lot of incidental contact and I think the kids are a huge factor in making a neighborhood feel, it creates an easy shared experience and proximity means you can easily help people out with eg shared babysitting. There's also a few people who make a dedicated effort to encourage community, like trick or treating, and it's a place where half the residents have been there over ten years. I joined the HOA in my first year which has definitely helped me get to know others.