We focussed a lot on async collaboration and unfortunately we get issues of team associations. You just miss out on any water cooler talk and struggle to build relationships with individual employees. This impacted our employee turnover massively even though we gave competitive salaries, flexible work hours and work-from-home.
- weekly all hands meetings where people talk about what makes them excited - lots of non-work-related chat rooms - 2-3 meetup opportunities per year - culture of quick ad-hoc synchronous meetings
We also had a board game night via Tabletop Simulator (http://berserk-games.com/tabletop-simulator/)
It also helps massively if the company is remote-first. We've got a central office where several employees are based but you never feel like you're missing out if you're based elsewhere.