That's interesting - a previous community I was involved in also considered using Croquet for rich interaction, but at the time the technology barriers were high (they probably still are, no ? I haven't checked it out recently).

What we did (well, they did mostly - I was in the wrong timezone and couldn't take part most of the time) - was simultaneous voice chat and collaborative document editing (with an application that allowed to work at several on a text file with different colors for each user).