Life Without The Breakroom
First, I've taken to doing individual check-ins with people that I'm not actively working with on projects, but with whom I have worked. Also on this list are people I generally chatted with at the office, regardless of whether we'd ever been on projects together. This little bit of contact certainly makes me feel better. Just a few lines back and for and then on with the rest of the day, but it gives me a boost. I started doing this when I realized that a non-work 'hello' from another co-worker had been a bright spot in my day.
Second, keeping a group chat open for something like 'shenanigans' is a great idea. My team has one, though I don't see it used as frequently as it could be. In times past a number of us from various teams maintained one that was solely for frivolity. It never took up much 'productivity time,' and was a nice aside to the use stressors of the day. While this might not be appealing to everyone, with the right combination of people it can be helpful for keeping a positive mood.
Third, a video conference can be an option. As I write this I realize that many might already have their fill of video meetings, and I get it. I use a headset on such calls to improve sound quality (input and output), and there comes a point I have to give my ears a break from being pressed against my head. That said, I've also been part of an occasional 30 minute call that a co-worker arranged just for some of us to relax and socialize. No work conversation is permitted, and we've mostly commiserated about life with social distancing and working from home. When I look at my calendar and see it's coming up, I feel a little sense of relief.
Those are my suggestions to make up for the missing social element in remote working. As time progresses we'll all surely have to adapt and come up with further strategies to make this work.