There is ongoing hope for the return of the much-loved story missions and freeplay modes. Conclusion
Be warned: In early 2024, a Discord group called "Survarium Reborn" claimed to have a working private server. They asked users to download a 40GB "custom client" and pay a $5 "access fee." The client was just the official game with a different splash screen. Users who installed it reported their Steam accounts were phished. Do not pay for access to a Survarium private server. Survarium Private Server
Some community members have preserved the final game files. You can find "launchers" that allow you to load into empty maps to see the environments and use different loadouts, but without AI or other players. There is ongoing hope for the return of