Remanum had certain problems, problems that the developers didn't see a way to change without massive rewrites. In a letter released to the community, the game director admits that without any further options, the team is going to shut down Remanum in the near future. Development and bug fixing have already stopped.
On September 16th, all servers except for the most recently opened server will be taken offline, with the newest server allowed to run a bit longer. Players can transfer to the last server starting now if they want to keep playing as long as possible. While this is a German server, support will be offered for all languages until the final shutdown, and any gold purchased on other servers will be transferred to this last bastion.
[Thanks to Arachnella for the tip!]