If you absolutely must test an old beta repack (for research or nostalgia), run it inside a Windows Sandbox, VMware, or VirtualBox with no shared folders and network disabled. This contains any potential malware.
Even if you download a repack from a forum with "good reputation," upload the .exe and .dll files to VirusTotal (multiple antivirus engines) before running. tantra kp beta 15b1 download repack top
A repack is a pre-configured, modified version of software — in this case, a Tantra game client + server emulator. Repacks are created by third-party users to make installation "easier" (no official installer needed). However, they come with severe risks: If you absolutely must test an old beta