You could point the DynDNS to your first server, generate a valid SSL certificate with letsencrypt, then move DynDNS and the certificate to the new server.
As per your update, the problem with the server is generating certificates, right?
Heavenltly Bodies is an astronaut simulator. You just have to pull levers and connect things, but with really cluncky and funny phisics which will make you LOL when someone pushes someone else the wrong way and they float into outer space and die.
There’s also a level with a mini spaceship that only has two seats. This level is great with at least 3 people. “Better hold on tight, buddy!”.
I think some of it is the audience’s fault. I have heard many friends complaining about multiplayer games being “dead” or “abandoned” because there’s no new content and I’m like “I’m pretty satisfied, it doesn’t need anything else”. If there’s enough people playing for matchmaking, I’m good.