After long back and forth consideration, and extensively testing various options (mainly various XMPP & IRC options and Matrix) this is the current take-away:
- Matrix is a buggy resource hog and thus unsuitable. The Web-client looks nice though.
- XMPP is working well and very light-weight on server resources, but currently caters to a very niche user group (esp. in regards to nice to use web and desktop clients). The Gateway to IRC is great, but otherwise bridging is relatively limited. Integrations in other services are ok, but could be better. As it is very lightweight, I will probably continue running a server, but I don't see it being a good way to attract new people to FreeGameDev or provide a credible alternative to Discord (more on that below).
- IRC has made some good improvements lately, but ultimately relies on a lot of not so well maintained legacy tech and is a bit of a headache to administer.
So all in all none of the above options really strike me as a way to renew this community, which is ultimately the goal of this little slow moving project of providing more modern web-services (besides learning how these things work on the side).
What I will try to set up next is Mattermost:
https://mattermost.com/Given that it is written in Go, it is reasonably resource efficient and has a nice modern chat interface with all the features people have come to expect. It also caters to a large extend to software developers and thus features a lot of nice integrations with Github/Gitlab etc. which is a good fit for our community ("linking open-source game developers with players").
It can also act as an IRC server, thus usage with IRC clients (some of which are really nice) is likely top-notch.
But the two main driving points are that it is very extendable with custom web-hooks and integrations of various stuff like Jitsi etc. and that its integration with the Matterbridge software is first grade. This currently allows near perfect bridging to Discord (and to a lesser grade of perfection many other chat services including XMPP, IRC and Matrix). I consider Discord to be especially important, as it is by far the service with the highest usage by the gaming community and even many open-source game development projects have opted to use it as their primary channel of communication. Thus as much as I personally don't like this non-Free service, realistically speaking there is currently no way around it. Mattermost/Matterbridge then seems to provide the smoothest interaction with it through FOSS tools and thus the best invitation to new users to switch to a Libre alternative.
The disadvantage of Mattermost is that it is non-federated and thus a single point of failure. I think we can mitigate this a bit by bridging to as many other services as possible, but I am not super happy about this.
Anyways, additional thoughts and comments on this topic are appreciated.