If you are a programmer, you can theoretically download the leaked Ikariam source code (circa 2012) from GitHub archives. However, hosting it requires PHP/MySQL knowledge, and you cannot run it for the public without facing legal action. This is only for offline learning.
Many "Ikariam private server links" do not lead to a game. They lead to a file download (e.g., "Launcher.exe" or "Register.dll"). Once run, this installs a cryptocurrency miner that uses your CPU to mine Monero while you think you are building a Crystal Mine. ikariam private server link