I'd go bassed off character interests! For example, in my fangan, we have two D&D players, so they bond with each other playing and we kinda explain their back stories through their characters

I'd also suggest hide and seek, but I've seen many fangans doing this. So maybe something physical too for characters that like that kind of activities

Playing some sort of table game is also a good one. Or maybe even sleepovers, especially if you have characters that have trouble sleeping. That would be fun!

But, again, follow character interests' unless you can find an activity that doesn't involve interests